Sample &
Buy
Product
Folder
Support &
Community
Tools &
Software
Technical
Documents
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
LMV221 50-MHz to 3.5-GHz 40-dB Logarithmic Power Detector for CDMA and WCDMA
1 Features
3 Description
•
•
•
•
•
•
•
•
The LMV221 is a 40-dB RF power detector intended
for use in CDMA and WCDMA applications. The
device has an RF frequency range from 50 MHz to
3.5 GHz. It provides an accurate temperature and
supply-compensated output voltage that relates
linearly to the RF input power in dBm. The circuit
operates with a single supply from 2.7 V to 3.3 V.
1
2.7-V to 3.3-V Supply Voltage
40-dB Linear in dB Power Detection Range
0.3-V to 2-V Output Voltage Range
Shutdown
Multi-Band Operation from 50 MHz to 3.5 GHz
0.5-dB Accurate Temperature Compensation
External Configurable Output Filter Bandwidth
2.5 mm × 2.2 mm × 0.8 mm 6-pin WSON
Package
2 Applications
•
•
•
•
UMTS/CDMA/WCDMA RF Power Control
GSM/GPRS RF Power Control
PA Modules
IEEE 802.11b, g (WLAN)
The LMV221 has an RF power detection range from
−45 dBm to −5 dBm and is ideally suited for direct
use in combination with a 30-dB directional coupler.
Additional low-pass filtering of the output signal can
be achieved by means of an external resistor and
capacitor. shows a detector with an additional output
low pass filter. The filter frequency is set with RS and
CS.
shows a detector with an additional feedback low
pass filter. Resistor RP is optional and lowers the
trans-impedance gain (RTRANS). The filter frequency is
set with CP//CTRANS and RP//RTRANS.
The device is active for Enable = High, otherwise it is
in a low power consumption shutdown mode. To save
power and prevent discharge of an external filter
capacitance, the output (OUT) is high-impedance
during shutdown.
Device Information(1)
PART NUMBER
LMV221
PACKAGE
BODY SIZE (NOM)
WSON (6)
2.50 mm × 2.20 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
space
space
Typical Application: Output RC Low Pass Filter
RF
COUPLER
ANTENNA
PA
space
RF
Typical Application: Feedback (R)C Low Pass Filter
COUPLER
50 :
50 :
VDD
VDD
RFIN
2
1
6
OUT
4
3
5
RS
RFIN
REF
2
+
CS
LMV221
EN
ANTENNA
PA
ADC
-
GND
Copyright © 2016, Texas Instruments Incorporated
1
6
OUT
LMV221
EN
4
3
+
RP
5
REF
CP
ADC
-
GND
Copyright © 2016, Texas Instruments Incorporated
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
6.1
6.2
6.3
6.4
6.5
6.6
6.7
7
1
1
1
2
3
4
Absolute Maximum Ratings ...................................... 4
ESD Ratings.............................................................. 4
Recommended Operating Conditions....................... 4
Thermal Information .................................................. 4
2.7-V DC and AC Electrical Characteristics.............. 5
Timing Requirements .............................................. 11
Typical Characteristics ............................................ 12
Detailed Description ............................................ 23
7.1 Overview ................................................................. 23
7.2 Functional Block Diagram ....................................... 23
7.3 Feature Description................................................. 23
7.4 Device Functional Modes........................................ 30
8
Application and Implementation ........................ 31
8.1 Application Information............................................ 31
8.2 Typical Applications ............................................... 34
9 Power Supply Recommendations...................... 38
10 Layout................................................................... 39
10.1 Layout Guidelines ................................................ 39
10.2 Layout Example .................................................... 41
11 Device and Documentation Support ................. 42
11.1
11.2
11.3
11.4
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
42
42
42
42
12 Mechanical, Packaging, and Orderable
Information ........................................................... 42
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision C (March 2013) to Revision D
Page
•
Added Device Information and Pin Configuration and Functions sections, ESD Ratings table and Thermal
Information table, Feature Description, Device Functional Modes, Application and Implementation, Power Supply
Recommendations, Layout, Device and Documentation Support, and Mechanical, Packaging, and Orderable
Information sections................................................................................................................................................................ 1
•
Changed RθJA value from 86.6°C/W to 100.4°C/W................................................................................................................. 4
Changes from Revision B (March 2013) to Revision C
•
2
Page
Changed layout of National Semiconductor data sheet to TI format.................................................................................... 41
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
5 Pin Configuration and Functions
NGF Package
6-Pin WSON
Top View
VDD
1
RFIN
2
GND
3
DAP
(GND)
6
OUT
5
REF
4
EN
Pin Functions
PIN
NUMBER
NAME
TYPE
1
VDD
3
GND
2
RFIN
Analog input
4
EN
Logic input
5
REF
6
OUT
DAP
GND
Power supply
Output
DESCRIPTION
Positive supply voltage
Power ground
RF input signal to the detector, internally terminated with 50 Ω.
The device is enabled for EN = high, and brought to a low-power shutdown
mode for EN = Low.
Reference output, for differential output measurement (without pedestal).
Connected to inverting input of output amplifier.
Ground referenced detector output voltage (linear in dB)
—
Ground (must be connected)
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
3
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
3.6
V
10
dBm
400
mV
SUPPLY VOLTAGE
VDD - GND
RF INPUT
Input power
DC voltage
Enable input voltage
VSS – 0.4 V < VEN < VDD + 0.4 V
Junction temperature (2)
Maximum lead temperature (soldering, 10 seconds)
Storage temperature, Tstg
(1)
(2)
–65
150
°C
260
°C
150
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
The maximum power dissipation is a function of TJ(MAX) , RθJA. The maximum allowable power dissipation at any ambient temperature is
PD = (TJ(MAX) – TA)/RθJA. All numbers apply for packages soldered directly into a PC board.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2000
Charged-device model (CDM), per JEDEC specification JESD22C101 (2)
±2000
Machine model
±200
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
MAX
UNIT
Supply voltage
2.7
3.3
V
Ambient temperature
–40
85
°C
RF frequency
RF input power (1)
(1)
50
3500
MHz
–45
–5
dBm
–58
–18
dBV
Power in dBV = dBm + 13 when the impedance is 50 Ω.
6.4 Thermal Information
LVM221
THERMAL METRIC (1)
NGF (WSON)
UNIT
6 PINS
RθJA
Junction-to-ambient thermal resistance (2)
100.4
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
120
°C/W
RθJB
Junction-to-board thermal resistance
7
°C/W
ψJT
Junction-to-top characterization parameter
69.6
°C/W
ψJB
Junction-to-board characterization parameter
6.9
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
69.9
°C/W
(1)
(2)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics, SPRA953.
The maximum power dissipation is a function of TJ(MAX) , RθJA. The maximum allowable power dissipation at any ambient temperature is
PD = (TJ(MAX) – TA)/RθJA. All numbers apply for packages soldered directly into a PC board.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
6.5 2.7-V DC and AC Electrical Characteristics
Unless otherwise specified, all limits are ensured at TA = 25°C, VDD = 2.7 V, RF input frequency ƒ = 1855-MHz continuous
wave (CW), modulated. (1)
MIN (2)
TYP (3)
MAX (2)
Active mode: EN = high, no signal present at RFIN
6.5
7.2
8.5
Active mode: EN = high, no signal present at RFIN
TA = –40°C to 85°C
5
PARAMETER
TEST CONDITIONS
UNIT
SUPPLY INTERFACE
IDD
Supply current
Shutdown: EN = low, no signal present at RFIN
10
0.5
Shutdown: EN = low, no signal present at RFIN
TA = –40°C to 85°C
EN = Low: PIN = 0 dBm
TA = –40°C to 85°C
mA
3
4
µA
(4)
10
LOGIC ENABLE INTERFACE
VLOW
EN logic low input level
(shutdown mode)
TA = –40°C to 85°C
VHIGH
EN logic high input level
TA = –40°C to 85°C
IEN
Current into EN pin
TA = –40°C to 85°C
0.6
V
1
µA
60
Ω
1.1
V
RF INPUT INTERFACE
RIN
(1)
(2)
(3)
(4)
Input resistance
40
47.1
2.7-V DC and AC Electrical Characteristics values apply only for factory testing conditions at the temperature indicated. Factory testing
conditions result in very limited self-heating of the device such that TJ = TA. No specification of parametric performance is indicated in
the electrical tables under conditions of internal self-heating where TJ > TA.
All limits are ensured by test or statistical analysis.
Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary
over time and also depend on the application and configuration. The typical values are not tested and are not specified on shipped
production material.
All limits are ensured by design and measurements which are performed on a limited number of samples. Limits represent the mean
±3–sigma values. The typical value represents the statistical mean value.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
5
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
2.7-V DC and AC Electrical Characteristics (continued)
Unless otherwise specified, all limits are ensured at TA = 25°C, VDD = 2.7 V, RF input frequency ƒ = 1855-MHz continuous
wave (CW), modulated.(1)
PARAMETER
TEST CONDITIONS
MIN (2)
TYP (3)
MAX (2)
16
40
UNIT
OUTPUT INTERFACE
From positive rail, sourcing,
VREF = 0 V, IOUT = 1 mA
VOUT
Output voltage swing
From positive rail, sourcing,
VREF = 0 V, IOUT = 1 mA
TA = –40°C to 85°C
50
mV
From negative rail, sinking,
VREF = 2.7 V, IOUT = 1 mA
14
From negative rail, sinking,
VREF = 2.7 V, IOUT = 1 mA
TA = –40°C to 85°C
Output short circuit
current
IOUT
3
Sourcing, VREF = 0 V, VOUT = 2.6 V
TA = –40°C to 85°C
2.7
Sinking, VREF = 2.7 V, VOUT = 0.1 V
3
Sinking, VREF = 2.7 V, VOUT = 0.1 V
TA = –40°C to 85°C
2.7
Small signal bandwidth
No RF input signal. Measured from REF input
current to VOUT
RTRANS
Output amplifier
transimpedance gain
No RF input signal, from IREF to VOUT, DC
SR
Slew rate
50
Sourcing, VREF = 0 V, VOUT = 2.6 V
BW
Output impedance (4)
IOUT,SD
Output leakage current in
shutdown mode
5.4
mA
5.7
450
35
42.7
Positive, VREF from 2.7 V to 0 V
3
4.1
Positive, VREF from 2.7 V to 0 V
TA = –40°C to 85°C
2.7
Negative, VREF from 0 V to 2.7 V
3
Negative, VREF from 0 V to 2.7 V
TA = –40°C to 85°C
2.7
No RF input signal, EN = High, DC measurement
ROUT
40
kHz
55
V/µs
4.2
0.6
No RF input signal, EN = High, DC measurement
TA = –40°C to 85°C
5
6
EN = Low, VOUT = 2 V
21
EN = Low, VOUT = 2 V
TA = –40°C to 85°C
kΩ
Ω
300
500
nA
RF DETECTOR TRANSFER
ƒ = 50 MHz, PIN= −5 dBm
ƒ = 50 MHz, PIN= −5 dBm
TA = –40°C to 85°
1.76
1.67
ƒ = 900 MHz, PIN= −5 dBm
ƒ = 900 MHz, PIN= −5 dBm
TA = –40°C to 85°C
1.75
1.67
ƒ = 1855 MHz, PIN= −5 dBm
VOUT,MAX
Maximum output
voltage (4)
ƒ = 1855 MHz, PIN= −5 dBm
TA = –40°C to 85°C
1.53
1.42
6
Submit Documentation Feedback
V
1.57
1.4
1.33
ƒ = 3500 MHz, PIN= −5 dBm
ƒ = 3500 MHz, TA = –40°C to 85°C
1.68
1.49
ƒ = 3000 MHz, PIN= −5 dBm
ƒ = 3000 MHz, PIN= −5 dBm
TA = –40°C to 85°C
1.82
1.61
ƒ = 2500 MHz, PIN= −5 dBm
ƒ = 2500 MHz, PIN= −5 dBm
TA = –40°C to 85°C
1.83
1.48
1.28
1.21
1.36
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
2.7-V DC and AC Electrical Characteristics (continued)
Unless otherwise specified, all limits are ensured at TA = 25°C, VDD = 2.7 V, RF input frequency ƒ = 1855-MHz continuous
wave (CW), modulated.(1)
MIN (2)
TYP (3)
MAX (2)
Minimum output voltage
(pedestal)
No input signal
175
250
350
No input signal, TA = –40°C to 85°C
142
388
Pedestal variation over
temperature
No input signal, relative to 25°C
TA = –40°C to 85°C
–20
20
PARAMETER
VOUT,MIN
TEST CONDITIONS
ƒ = 50 MHz, PIN from −45 dBm to −5 dBm
ƒ = 50 MHz, PIN from −45 dBm to −5 dBm
TA = –40°C to 85°C
1.37
Output voltage range (4)
ƒ = 1855 MHz, PIN from −45 dBm to −5 dBm
TA = –40°C to +85°C
1.34
1.24
1.14
ƒ = 50 MHz
KSLOPE
PINT
Logarithmic slope (4)
Logarithmic intercept (4)
en
Output referred noise (5)
vN
(4)
Output referred noise
1.3
1.07
1.2
1.01
0.96
1.09
39
40.5
ƒ = 900 MHz
36.7
38.5
40
ƒ = 1855 MHz
34.4
35.7
37.1
ƒ = 2500 MHz
32.6
33.8
35.2
ƒ = 3000 MHz
31
32.5
34
ƒ = 3500 MHz
30
31.9
33.5
ƒ = 50 MHz
–50.4
−49.4
–48.3
ƒ = 900 MHz
–54.1
−52.8
–51.6
ƒ = 1855 MHz
–53.2
−51.7
–50.2
ƒ = 2500 MHz
–51.8
−50
–48.3
ƒ = 3000 MHz
–51.1
−48.9
–46.6
ƒ = 3500 MHz
–49.6
−46.8
–44.1
PIN = −10 dBm at 10 kHz
1.5
Integrated over frequency band, 1 kHz to 6.5 kHz
100
Integrated over frequency band, 1 kHz to 6.5 kHz
TA = –40°C to 85°C
PSRR
(5)
Power supply rejection
ratio (5)
V
1.12
ƒ = 3500 MHz, PIN from −45 dBm to −5 dBm
ƒ = 3500 MHz, PIN from −45 dBm to −5 dBm
TA = –40°C to 85°C
1.37
1.2
ƒ = 3000 MHz, PIN from −45 dBm to −5 dBm
ƒ = 3000 MHz, PIN from −45 dBm to −5 dBm
TA = –40°C to 85°C
1.47
1.3
ƒ = 2500 MHz, PIN from −45 dBm to −5 dBm
ƒ = 2500 MHz, PIN from −45 dBm to −5 dBm
TA = –40°C to 85°C
1.52
1.4
ƒ = 1855 MHz, PIN from −45 dBm to −5 dBm
ΔVOUT
42
mV/dB
dBm
µV/√Hz
150
PIN = −10 dBm, ƒ = 1800 MHz
PIN = −10 dBm, ƒ = 1800 MHz
TA = –40°C to 85°C
mV
1.44
ƒ = 900 MHz, PIN from −45 dBm to −5 dBm
ƒ = 900 MHz, PIN from −45 dBm to −5 dBm
TA = –40°C to 85°C
UNIT
µVRMS
60
55
dB
This parameter is ensured by design and/or characterization and is not tested in production.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
7
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
2.7-V DC and AC Electrical Characteristics (continued)
Unless otherwise specified, all limits are ensured at TA = 25°C, VDD = 2.7 V, RF input frequency ƒ = 1855-MHz continuous
wave (CW), modulated.(1)
PARAMETER
TEST CONDITIONS
MIN (2)
TYP (3)
MAX (2)
UNIT
POWER MEASUREMENT PERFORMANCE
ƒ = 50 MHz
−40 dBm ≤ PIN ≤ −10 dBm
–0.6
ƒ = 50 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–1.1
ƒ = 900 MHz
−40 dBm ≤ PIN ≤ −10 dBm
–0.7
ƒ = 900 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
ELC
Log conformance error (4)
ƒ = 1855 MHz
−40 dBm ≤ PIN ≤ −10 dBm
–0.4
ƒ = 1855 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–1.1
ƒ = 2500 MHz
−40 dBm ≤ PIN ≤ −10 dBm
ƒ = 2500 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
ƒ = 3000 MHz
−40 dBm ≤ PIN ≤ −10 dBm
ƒ = 3000 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
ƒ = 3500 MHz
−40 dBm ≤ PIN ≤ −10 dBm
ƒ = 3500 MHz, TA = –40°C to 85°C
E1
8
dB
Measurement error for a
1-dB Input power step (4)
0.37
0.46
0.48
1.1
0.51
1.1
1.34
0.56
–1.73
1.6
2.72
2.7
–1.1
0.4
1.4
–1
0.38
1.27
ƒ = 1855 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–1.1
0.44
1.31
ƒ = 2500 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–1.1
0.48
1.15
ƒ = 3000 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–1.2
0.5
0.98
ƒ = 3500 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–1.2
0.62
0.85
dB
ƒ = 50 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–0.06
0.069
ƒ = 900 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–0.056
0.056
ƒ = 1855 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–0.069
0.069
ƒ = 2500 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–0.084
0.084
ƒ = 3000 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–0.092
0.092
ƒ = 3500 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–0.1
0.1
Submit Documentation Feedback
dB
0.56
–0.87
–1.2
1.1
0.24
–0.43
–1
1.3
0.84
ƒ = 900 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
EVOT
0.53
–2
ƒ = 50 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
Variation over
temperature (4)
–1.24
0.56
dB
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
2.7-V DC and AC Electrical Characteristics (continued)
Unless otherwise specified, all limits are ensured at TA = 25°C, VDD = 2.7 V, RF input frequency ƒ = 1855-MHz continuous
wave (CW), modulated.(1)
PARAMETER
E10 dB
TEST CONDITIONS
MIN (2)
–0.65
0.57
ƒ = 900 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–0.75
0.58
–0.88
0.72
–0.86
0.75
ƒ = 3000 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–0.85
0.77
ƒ = 3500 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
–0.76
0.74
ƒ = 1855 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
Measurement Error for a
10-dB Input power step (4) ƒ = 2500 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
ƒ = 50 MHz, −40°C < TA < 25°C
(4)
ƒ = 900 MHz, −40°C < TA < 25°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
–7
–15
–13.4
–14.1
–13.4
–10.5
ST
Temperature sensitivity
–12.3
–13.1
–14.7
0.42
mdB/°C
–7.6
–15.9
0.63
–8.5
–18
ƒ = 3500 MHz, −40 dBm ≤ PIN ≤ −10 dBm
ƒ = 3500 MHz, 25°C < TA < 85°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
–0.2
–7.1
ƒ = 3000 MHz, −40 dBm ≤ PIN ≤ −10 dBm
ƒ = 3000 MHz, 25°C < TA < 85°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
–1.1
–6.7
ƒ = 2500 MHz,−40 dBm ≤ PIN ≤ −10 dBm
ƒ = 2500 MHz, 25°C < TA < 85°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
1.2
–6.7
ƒ =1855 MHz, −40 dBm ≤ PIN ≤ −10 dBm
ƒ =1855 MHz, 25°C < TA < 85°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
8
0.5
ƒ = 900 MHz, −40 dBm ≤ PIN ≤ −10 dBm
ƒ = 900 MHz, 25°C < TA < 85°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
5.2
–11.7
ƒ = 50 MHz, −40 dBm ≤ PIN ≤ −10 dBm
ƒ = 50 MHz, 25°C < TA < 85°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
mdB/°C
–1.8
ƒ = 3500 MHz, −40 dBm ≤ PIN ≤ −10 dBm
ƒ = 3500 MHz, −40°C < TA < 25°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
2.3
–4.1
ƒ = 3000 MHz, −40 dBm ≤ PIN ≤ −10 dBm
ƒ = 3000 MHz, −40°C < TA < 25°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
1.5
–5.9
ƒ = 2500 MHz,−40 dBm ≤ PIN ≤ −10 dBm
ƒ = 2500 MHz, −40°C < TA < 25°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
1
–6
ƒ = 1855 MHz, −40 dBm ≤ PIN ≤ −10 dBm
ƒ = 1855 MHz, −40°C < TA < 25°C
−40 dBm ≤ PIN ≤ −10 dBm (4)
UNIT
dB
ƒ = 900 MHz,−40 dBm ≤ PIN ≤ −10 dBm
Temperature sensitivity
MAX (2)
ƒ = 50 MHz, TA = –40°C to 85°C
−40 dBm ≤ PIN ≤ −10 dBm
ƒ = 50 MHz, −40 dBm ≤ PIN ≤ −10 dBm
ST
TYP (3)
1
–9.5
–21.2
2.5
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
9
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
2.7-V DC and AC Electrical Characteristics (continued)
Unless otherwise specified, all limits are ensured at TA = 25°C, VDD = 2.7 V, RF input frequency ƒ = 1855-MHz continuous
wave (CW), modulated.(1)
PARAMETER
TEST CONDITIONS
MIN (2)
ƒ = 50 MHz, PIN = −10 dBm
ƒ = 50 MHz, –40°C < TA < 25°C
PIN = −10 dBm (4)
–15.8
ST
Temperature sensitivity (4)
–14.9
–14.5
ST
Temperature sensitivity (4)
–12
–12.4
–13.7
–14.6
–15.2
–6.5
–12.2
–16.5
–7.9
–13.5
–18.1
–9
–8.85
ƒ = 900 MHz
–6.1
ƒ = 900 MHz, MIN at TA = –40°C to 85°C
–9.3
ƒ = 1855 MHz
ƒ = 1855 MHz, TA = –40°C to 85°C
–5.5
–8.3
ƒ = 2500 MHz
ƒ = 2500 MHz, TA = –40°C to 85°C
–4.2
ƒ = 3000 MHz, TA = –40°C to 85°C
–3.7
–5.4
ƒ = 3500 MHz
ƒ = 3500 MHz, TA = –40°C to 85°C
Submit Documentation Feedback
dBm
–6
ƒ = 3000 MHz
10
mdB/°C
–5.9
ƒ = 50 MHz, TA = –40°C to 85°C
Maximum input power
for ELC = 1 dB (4)
–5.6
–10.8
ƒ = 50 MHz
PMAX
–5
–10
ƒ = 3500 MHz, PIN = −10 dBm
ƒ = 3500 MHz, 25°C < TA < 85°C
PIN = −10 dBm (4)
–5.3
–9.4
ƒ = 3000 MHz, PIN = −10 dBm
ƒ = 3000 MHz, 25°C < TA < 85°C
PIN = −10 dBm (4)
5.3
–8.9
ƒ = 2500 MHz, PIN = −10 dBm
ƒ = 2500 MHz, 25°C < TA < 85°C
PIN = −10 dBm (4)
3.3
–3.4
ƒ = 1855 MHz, PIN = −10 dBm
ƒ = 1855 MHz, 25°C < TA < 85°C
PIN = −10 dBm (4)
1.3
–13
ƒ = 900 MHz, PIN = −10 dBm
ƒ = 900 MHz, 25°C < TA < 85°C
PIN = −10 dBm (4)
mdB/°C
–4.9
ƒ = 50 MHz, PIN = −10 dBm
ƒ = 50 MHz, 25°C < TA < 85°C
PIN = −10 dBm (4)
2
–6.6
ƒ = 3500 MHz, PIN = −10 dBm
ƒ = 3500 MHz, –40°C < TA < 25°C
PIN = −10 dBm (4)
2.2
–7.4
ƒ = 3000 MHz, PIN = −10 dBm
ƒ = 3000 MHz, –40°C < TA < 25°C
PIN = −10 dBm (4)
–0.75
–14.2
ƒ = 2500 MHz, PIN = −10 dBm
ƒ = 2500 MHz, –40°C < TA < 25°C
PIN = −10 dBm (4)
UNIT
–6
ƒ = 1855 MHz, PIN = −10 dBm
ƒ = 1855 MHz, –40°C < TA < 25°C
PIN = −10 dBm (4)
MAX (2)
–8.3
ƒ = 900 MHz, PIN = −10 dBm
ƒ = 900 MHz, –40°C < TA < 25°C
PIN = −10 dBm (4)
TYP (3)
–2.7
–7.2
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
2.7-V DC and AC Electrical Characteristics (continued)
Unless otherwise specified, all limits are ensured at TA = 25°C, VDD = 2.7 V, RF input frequency ƒ = 1855-MHz continuous
wave (CW), modulated.(1)
PARAMETER
TEST CONDITIONS
MIN (2)
ƒ = 50 MHz
TYP (3)
MAX (2)
ƒ = 50 MHz, TA = –40°C to 85°C
–38.9
ƒ = 900 MHz
–44.2
ƒ = 900 MHz, MIN at TA = –40°C to 85°C
–42.9
ƒ = 1855 MHz
PMIN
Minimum input power for
ELC = 1 dB (4)
–42.9
ƒ = 1855 MHz, TA = –40°C to 85°C
–41.2
ƒ = 2500 MHz
–40.4
ƒ = 2500 MHz, TA = –40°C to 85°C
–38.4
ƒ = 3000 MHz, TA = –40°C to 85°C
–35.8
ƒ = 3500 MHz
–35.3
ƒ = 3500 MHz, TA = –40°C to 85°C
–31.9
ƒ = 50 MHz
34.5
ƒ = 50 MHz, TA = –40°C to 85°C
31.5
ƒ = 900 MHz
38.1
ƒ = 900 MHz, MIN at TA = –40°C to 85°C
34.4
ƒ = 1855 MHz
Dynamic range for ELC =
1 dB (4)
dBm
–38.6
ƒ = 3000 MHz
DR
UNIT
–40.3
ƒ = 1855 MHz, TA = –40°C to 85°C
37.4
34
ƒ = 2500 MHz
ƒ = 2500 MHz, TA = –40°C to 85°C
33.8
ƒ = 3000 MHz
ƒ = 3000 MHz, TA = –40°C to 85°C
34.8
32.4
ƒ = 3500 MHz
ƒ = 3500 MHz, TA = –40°C to 85°C
dB
36.1
32.7
26.2
6.6 Timing Requirements
MIN
Turnon time, no signal at PIN, low-high transition EN, VOUT to 90% (1)
tON
(1)
(2)
10
12
Rise time , PIN = no signal to 0 dBm, VOUT from 10% to 90%
TA = –40°C to 85°C
Fall time (2), PIN = no signal to 0 dBm, VOUT from 90% to 10%
TA = –40°C to 85°C
UNIT
µs
2
(2)
Fall time (2), PIN = no signal to 0 dBm, VOUT from 90% to 10%
tF
MAX
8
Turnon time, no signal at PIN, low-high transition EN, VOUT to 90% (1)
TA = –40°C to 85°C
Rise time (2), PIN = no signal to 0 dBm, VOUT from 10% to 90%
tR
NOM
12
µs
2
12
µs
All limits are ensured by design and measurements, which are performed on a limited number of samples. Limits represent the mean
±3-sigma values. The typical value represents the statistical mean value.
This parameter is ensured by design and/or characterization and is not tested in production.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
11
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
6.7 Typical Characteristics
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
10
10
85°C
25°C
-40°C
SUPPLY CURRENT (mA)
8
8
ISUPPLY (mA)
85°C
6
4
6
25°C
-40°C
4
2
2
0
2.2
2.5
2.8
3.1
0
650
3.4
700
SUPPLY VOLTAGE (V)
900
45
-40°C
45
LOGARITHMIC SLOPE (mV/dB)
2.0
1855 MHz
1.6
1.6
900 MHz
VOUT (V)
850
Figure 2. Supply Current vs Enable Voltage
2.0
1.2
1.2
2500 MHz
0.8
0.8
3000 MHz
0.4
3500 MHz
0.4
0.0
25°C
40
40
85°C
3535
30
30
25
25
0.0
-60
-50
-40
-30
-20
-10
0
10M
10
RF INPUT POWER (dBm)
1G
10G
Figure 4. Log Slope vs Frequency
-38
-38
2.0
-40°C
VOUT (V)
-42
-42
-46
-46
25°C
-50
-50
100M
FREQUENCY (Hz)
Figure 3. Output Voltage vs RF Input Power
LOGARITHMIC INTERCEPT (dBm)
800
VENABLE (mV)
Figure 1. Supply Current vs Supply Voltage
RFIN = - 5 dBm
1.6
RFIN = -15 dBm
1.2
RFIN = -25 dBm
0.8
RFIN = -35 dBm
85°C
0.4
RFIN = -45 dBm
-54
-54
10M
10M
100M
1G
100M
1G
FREQUENCY (Hz)
10G
10G
0.0
10M
100M
1G
10G
FREQUENCY (Hz)
Figure 5. Log Intercept vs Frequency
12
750
Submit Documentation Feedback
Figure 6. Output Voltage vs Frequency
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Typical Characteristics (continued)
2.0
1.6
1.5
-40°C
1.0
25°C
1.2
1.0
0.5
0.0
85°C
0.8
-0.5
0.6
-1.0
0.4
-45
-2.0
-25
-15
-5
1.5
-40°C
1.4
1.0
-0.5
-1.0
-45
-2.5
-35
-25
-15
-5
5
RF INPUT POWER (dBm)
2.0
1.5
-40°C
1.4
1.2
1.0
0.5
25°C
1.0
0.0
85°C
0.8
-0.5
0.6
-1.0
0.4
-1.5
85°C
25°C
0.2
-2.0
-40°C
-45
Figure 8. Mean Output Voltage and Log Conformance Error
vs RF Input Power
-25
-15
-5
2.5
1.8
2.0
1.6
1.5
0.5
85°C
1.0
0.0
0.8
-0.5
0.6
-1.0
-1.5
85°C
0.2
0.0
-55
5
-2.0
25°C
-40°C
-2.5
-45
RF INPUT POWER (dBm)
-35
-25
-15
-5
5
RF INPUT POWER (dBm)
2500 MHz
2.0
2.5
1.8
2.0
1.6
1.5
1.4
1.0
-40°C 25°C
1.2
0.5
1.0
0.0
0.8
-0.5
0.6
-1.0
85°C
0.4
-1.5
85°C
0.2
-40°C
-2.0
25°C
LOG CONFORMANCE ERROR (dB)
Figure 9. Mean Output Voltage and Log Conformance Error
vs RF Input Power
-2.5
-35
-25
-15
-5
5
Figure 10. Mean Output Voltage and Log Conformance Error
vs RF Input Power
2.0
2.5
1.8
2.0
1.5
1.6
1.4
VOUT (V)
1855 MHz
-45
1.0
-40°C 25°C
1.2
0.4
-2.5
-35
2.0
1.4
VOUT (V)
2.5
1.8
LOG CONFORMANCE ERROR (dB)
2.0
1.6
VOUT (V)
-2.0
-40°C
900 MHz
Figure 7. Mean Output Voltage and Log Conformance Error
vs RF Input Power
VOUT (V)
-1.5
85°C
25°C
RF INPUT POWER (dBm)
0.0
-55
0.0
85°C
0.6
0.0
-55
50 MHz
0.0
-55
0.5
0.8
0.2
5
1.0
25°C
1.2
0.4
-2.5
-35
2.0
1.6
LOG CONFORMANCE ERROR (dB)
0.0
-55
-1.5
85°C
25°C
-40°C
0.2
2.5
1.8
-40°C
1.2
1.0
25°C
0.5
1.0
0.0
0.8
-0.5
-1.0
0.6
85°C
0.4
0.0
-55
-1.5
85°C
0.2
-40°C
-45
RF INPUT POWER (dBm)
-2.0
25°C
LOG CONFORMANCE ERROR (dB)
VOUT (V)
1.4
2.0
LOG CONFORMANCE ERROR (dB)
2.5
1.8
VOUT (V)
2.0
LOG CONFORMANCE ERROR (dB)
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
-2.5
-35
-25
-15
-5
5
RF INPUT POWER (dBm)
3000 MHz
3500 MHz
Figure 11. Mean Output Voltage and Log Conformance Error
vs RF Input Power
Figure 12. Mean Output Voltage and Log Conformance Error
vs RF Input Power
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
13
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Typical Characteristics (continued)
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
50 MHz
900 MHz
Figure 13. Log Conformance Error (Mean ±3 Sigma) vs RF
Input Power
1855 MHz
2500 MHz
Figure 15. Log Conformance Error (Mean ±3 Sigma) vs RF
Input Power
3000 MHz
Figure 16. Log Conformance Error (Mean ±3 Sigma) vs RF
Input Power
3500 MHz
Figure 17. Log Conformance Error (Mean ±3 Sigma) vs RF
Input Power
14
Figure 14. Log Conformance Error (Mean ±3 Sigma) vs RF
Input Powert
Figure 18. Log Conformance Error (Mean ±3 Sigma) vs RF
Input Power
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Typical Characteristics (continued)
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
1.5
1.5
1.0
TEMPERATURE DRIFT ERROR (dB)
TEMPERATURE DRIFT ERROR (dB)
1.5
-40°C
1.0
0.5
0.5
0.0
0.0
-0.5
-0.5
-1.0
85°C
-1.5
-1.0
-1.5
1.5
1.0
-40°C
1.0
0.5
0.5
0.0
0.0
-0.5
-0.5
-1.0
85°C
-1.5
-1.0
-1.5
-55
-45
-35
-25
-15
-5
5
-55
-45
RF INPUT POWER (dBm)
50 MHz
-15
-5
5
Figure 20. Mean Temperature Drift Error vs RF Input Power
1.5
1.5
TEMPERATURE DRIFT ERROR (dB)
TEMPERATURE DRIFT ERROR (dB)
-25
900 MHz
Figure 19. Mean Temperature Drift Error vs Rf Input Power
At 50 MHz
1.5
1.0
-40°C
1.0
0.5
0.5
0.0
0.0
-0.5
-0.5
-1.0
85°C
-1.5
-1.0
1.5
1.0
1.0
-55
-45
-35
-25
-15
-5
-40°C
0.5
0.5
0.0
0.0
-0.5
-0.5
-1.0
85°C
-1.5
-1.0
-1.5
-1.5
5
-55
-45
-35
-25
-15
-5
5
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
2500 MHz
1855 MHz
Figure 21. Mean Temperature Drift Error vs RF Input Power
Figure 22. Mean Temperature Drift Error vs RF Input Powert
1.5
1.5
TEMPERATURE DRIFT ERROR (dB)
TEMPERATURE DRIFT ERROR (dB)
-35
RF INPUT POWER (dBm)
1.5
1.0
1.0
0.5
0.5
-40°C
0.0
0.0
-0.5
-0.5
-1.0
85°C
-1.5
-1.0
-1.5
1.5
1.0
1.0
0.5
0.5
-40°C
0.0
0.0
-0.5
-0.5
-1.0
-1.5
-1.0
85°C
-1.5
-55
-45
-35
-25
-15
-5
5
-55
RF INPUT POWER (dBm)
-45
-35
-25
-15
-5
5
RF INPUT POWER (dBm)
3000 MHz
3500 MHz
Figure 23. Mean Temperature Drift Error vs RF Input Power
Figure 24. Mean Temperature Drift Error vs RF Input Power
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
15
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Typical Characteristics (continued)
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
50 MHz
900 MHz
Figure 25. Temperature Drift Error (Mean ±3 Sigma) vs RF
Input Power
1855 MHz
2500 MHz
Figure 27. Temperature Drift Error (Mean ±3 Sigma) vs RF
Input Power
3000 MHz
Figure 28. Temperature Drift Error (Mean ±3 Sigma) vs RF
Input Power
3500 MHz
Figure 29. Temperature Drift Error (Mean ±3 Sigma) vs RF
Input Power
16
Figure 26. Temperature Drift Error (Mean ±3 Sigma) vs RF
Input Power
Figure 30. Temperature Drift Error (Mean ±3 Sigma) vs RF
Input Power
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Typical Characteristics (continued)
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
0.3
0.3
0.2
0.2
1 dB POWER STEP ERROR (dB)
1 dB POWER STEP ERROR (dB)
0.3
-40°C
0.1
0.1
0.0
0.0
-0.1
-0.1
-0.2
25°C
85°C
-0.3
-0.2
-0.3
-55
-45
-35
-25
-15
-5
0.3
0.2
0.2
0.1
0.1
0.0
0.0
-55
Figure 31. Error For 1-dB Input Power Step vs RF Input
Power
5
Figure 32. Error For 1-dB Input Power Step vs RF Input
Power
0.3
1 dB POWER STEP ERROR (dB)
0.3
1 dB POWER STEP ERROR (dB)
-45
-35
-25
-15
-5
RF INPUT POWER (dBm)
900 MHz
50 MHz
0.3
0.2
-40°C
0.2
0.1
0.1
0.0
0.0
85°C
25°C
-0.1
-0.1
-0.2
-0.2
-0.3
0.3
0.2
-40°C
0.2
0.1
0.1
0.0
0.0
25°C
-0.1
-0.1
-0.2
85°C
-0.3
-0.2
-0.3
-0.3
-55
-45
-35
-25
-15
-5
-55
5
RF INPUT POWER (dBm)
-45
-35
-25
-15
-5
RF INPUT POWER (dBm)
5
2500 MHz
1855 MHz
Figure 33. Error For 1-dB Input Power Step vs RF Input
Power
Figure 34. Error For 1-dB Input Power Step vs RF Input
Power
0.3
0.3
0.3
0.2
0.2
1 dB POWER STEP ERROR (dB)
1 dB POWER STEP ERROR (dB)
85°C
-0.3
-0.2
RF INPUT POWER (dBm)
-40°C
0.1
0.1
0.0
0.0
-0.1
-0.1
-0.2
25°C
85°C
-0.3
-0.2
-0.3
25°C
-0.1
-0.1
-0.2
-0.3
5
-40°C
-55
-45
-35
-25
-15
-5
RF INPUT POWER (dBm)
0.3
0.2
-40°C
0.2
0.1
0.1
0.0
0.0
25°C
-0.1
-0.1
-0.2
85°C
-0.3
-0.2
-0.3
5
-55
-45
-35
-25
-15
-5
5
RF INPUT POWER (dBm)
3000 MHz
3500 MHz
Figure 35. Error For 1-dB Input Power Step vs RFInput
Power
Figure 36. Error For 1-dB Input Power Step vs RF Input
Power
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
17
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Typical Characteristics (continued)
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
1.00
1.00
10 dB POWER STEP ERROR (dB)
10 dB POWER STEP ERROR (dB)
-40°C
0.75
1.00
0.50
0.75
0.50
0.25
0.25
0.00
0.00
-0.25
-0.25
-0.50
-0.75
-0.50
-1.00
25°C
85°C
-0.75
-1.00
0.75
1.00
0.50
0.75
0.50
0.25
0.25
0.00
0.00
-0.25
-0.25
-0.50
-0.75
-0.50
-1.00
-40°C
25°C
85°C
-0.75
-1.00
-60
-50
-40
-30
-20
-10
-60
0
-50
-40
-30
-20
-10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
900 MHz
50 MHz
Figure 37. Error For 10-dB Input Power Step vs RF Input
Power
Figure 38. Error For 10-dB Input Power Step vs RF Input
Power
1.00
1.00
25°C
10 dB POWER STEP ERROR (dB)
10 dB POWER STEP ERROR (dB)
-40°C
0.75
1.00
0.50
0.75
0.50
0.25
0.25
0.00
0.00
-0.25
-0.25
-0.50
-0.75
-0.50
-1.00
25°C
85°C
-0.75
-1.00
0.75
1.00
0.50
0.75
0.50
0.25
0.25
0.00
0.00
-0.25
-0.25
-0.50
-0.75
-0.50
-1.00
-40°C
85°C
-0.75
-1.00
-60
-50
-40
-30
-20
-10
0
-60
-50
RF INPUT POWER (dBm)
-30
-20
-10
0
2500 MHz
Figure 39. Error For 10-dB Input Power Step vs RF Input
Power
Figure 40. Error For 10-dB Input Power Step vs RF Input
Power
1.00
1.00
0.75
1.00
0.50
0.75
0.50
0.25
0.25
0.00
0.00
-0.25
-0.25
-0.50
-0.75
-0.50
-1.00
10 dB POWER STEP ERROR (dB)
-40°C
10 dB POWER STEP ERROR (dB)
-40
RF INPUT POWER (dBm)
1855 MHz
25°C
85°C
-0.75
-1.00
-40°C
0.75
1.00
0.50
0.75
0.50
0.25
0.25
0.00
0.00
-0.25
-0.25
-0.50
-0.75
-0.50
-1.00
25°C
85°C
-0.75
-1.00
-60
-50
-40
-30
-20
-10
0
-60
RF INPUT POWER (dBm)
-50
-40
-30
-20
-10
0
RF INPUT POWER (dBm)
3000 MHz
3500 MHz
Figure 41. Error For 10-dB Input Power Step vs RF Input
Power
18
0
Figure 42. Error For 10-dB Input Power Step vs RF Input
Power
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Typical Characteristics (continued)
20
20
15
20
10
15
10
55
0
0
-5
-10
-5
-15
-10
-20
TEMPERATURE SENSITIVITY (mdB/°C)
TEMPERATURE SENSITIVITY (mdB/°C)
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
-40°C
-30°C
85°C
-15
-20
-55
-45
-35
-25
-15
-5
15
20
10
15
10
5
5
00
-5
-5
-10
-40°C
-30°C
-15
-10
-20
85°C
-15
-20
5
-55
RF INPUT POWER (dBm)
-25
-15
-5
5
900 MHz
Figure 43. Mean Temperature Sensitivity vs RF Input Power
Figure 44. Mean Temperature Sensitivity vs RF Input Power
20
20
15
20
10
15
10
5
5
00
-5
-5
-10
-15
-10
-20
TEMPERATURE SENSITIVITY (mdB/°C)
TEMPERATURE SENSITIVITY (mdB/°C)
-35
RF INPUT POWER (dBm)
50 MHz
-40°C
-30°C
85°C
-15
15
20
10
15
10
5
5
00
-5
-5
-10
-15
-10
-20
-40°C
-30°C
85°C
-15
-20
-20
-55
-45
-35
-25
-15
-5
-55
5
RF INPUT POWER (dBm)
-45
-35
-25
-15
-5
5
RF INPUT POWER (dBm)
1855 MHz
2500 MHz
Figure 45. Mean Temperature Sensitivity vs RF Input Power
Figure 46. Mean Temperature Sensitivity vs RF Input Power
20
TEMPERATURE SENSITIVITY (mdB/°C)
20
TEMPERATURE SENSITIVITY (mdB/°C)
-45
15
20
10
15
510
5
00
-5
-5
-10
-15
-10
-20
-40°C
-30°C
85°C
-15
15
20
10
15
10
5
5
00
-5
-5
-10
-40°C
85°C
-30°C
-15
-10
-20
-15
-20
-20
-55
-45
-35
-25
-15
-5
-55
5
-45
-35
-25
-15
-5
5
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
3500 MHz
3000 MHz
Figure 47. Mean Temperature Sensitivity vs RF Input Power
Figure 48. Mean Temperature Sensitivity vs RF Input Power
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
19
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Typical Characteristics (continued)
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
50 MHz
900 MHz
Figure 49. Temperature Sensitivity (Mean ±3 Sigma) vs RF
Input Power
1855 MHz
2500 MHz
Figure 51. Temperature Sensitivity (Mean ±3 Sigma) vs RF
Input Power
3000 MHz
Figure 52. Temperature Sensitivity (Mean ±3 Sigma) vs RF
Input Power
3500 MHz
Figure 53. Temperature Sensitivity (Mean ±3 Sigma) vs RF
Input Power
20
Figure 50. Temperature Sensitivity (Mean ±3 Sigma) vs RF
Input Power
Figure 54. Temperature Sensitivity (Mean ±3 Sigma) vs RF
Input Power
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Typical Characteristics (continued)
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
2.5
IS-95
1.6
2.0
1.41.8
1.6
1.21.4
1.2
1.01.0
0.8
0.80.6
0.4
0.60.2
0.0
0.4
WCDMA 64 CH
CW
1.5
2.5
2.0
1.0
1.5
1.0
0.5
0.5
0.0
0.0
-0.5
-1.0
-0.5
-1.5
-2.0
-1.0
-2.5
-1.5
WCDMA 64 ch IS-95
0.2
-2.0
0.0
-45
-35
-25
-15
-5
RF INPUT POWER (dBm)
2.0
IS-95
1.6
2.0
1.41.8
1.6
1.21.4
1.2
1.0
1.00.8
0.6
0.8
0.4
0.2
0.6
0.0
1.5
2.5
1.0
2.0
1.5
1.0
0.5
0.5
0.0
0.0
-0.5
-1.0
-0.5
-1.5
-2.0
-1.0
-2.5
-1.5
WCDMA 64 CH
CW
0.4
IS-95
-2.0
WCDMA 64 ch
-2.5
0.0
5
-55
900 MHz
-45
-35
-25
-15
-5
RF INPUT POWER (dBm)
5
1855 MHz
Figure 55. Output Voltage and Log Conformance Error vs
RR Input Power for Various Modulation Types
Figure 56. Output Voltage and Log Conformance Error vs
RF Input Power for Various Modulation Types
100
10
9
75
100
5075
50
25
25
0 0
-25
-25
-50
-75
-50
-100
R
8
VOLTAGE NOISE (µV/ Hz)
RF INPUT IMPEDANCE ( )
CW
0.2
-2.5
-55
2.5
2.0
1.8
VOUT (V)
VOUT (V)
2.0
LOG CONFORMANCE ERROR (dB)
CW
LOG CONFORMANCE ERROR (dB)
2.0
1.8
X
7
6
5
4
3
2
-75
1
-100
100M
1G
0
10
10G
100
FREQUENCY (Hz)
Figure 57. RF Input Impedance vs Frequency (Resistance
and Reactance)
10k
100k
1M
Figure 58. Output Noise Spectrum vs Frequency
80
270
100k
GAIN
70
80
60
70
60
50
50
4040
30
3020
10
20
0
TRANS IMPEDANCE GAIN
PSRR (dB)
1k
FREQUENCY (Hz)
225
180
10k
135
PHASE
90
PHASE (°)
10M
45
1k
0
-45
10
100
100
0
10
100
1k
10k
100k
FREQUENCY (Hz)
1M
1k
10k
100k
1M
-90
10M
FREQUENCY (Hz)
Figure 59. Power Supply Rejection Ratio vs Frequency
Figure 60. Output Amplifier Gain and Phase vs Frequency
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
21
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Typical Characteristics (continued)
Unless otherwise specified, VDD = 2.7V, TA = 25°C, measured on a limited number of samples.
60
25°C
85°C
50
-40°C
40
30
20
10
0
0.0
0.5
1.0
1.5
2.0
25°C
SINKING OUTPUT CURRENT (mA)
SOURCING OUTPUT CURRENT (mA)
60
2.5
-40°C
40
30
20
10
0
0.0
3.0
0.5
1.0
1.5
VOUT (V)
2.5
3.0
Figure 62. Sinking Output Current vs Output Voltage
2.70
0.08
-40°C
-40°C
2.68
2.70
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
2.0
VOUT (V)
Figure 61. Sourcing Output Current vs Output Voltage
25°C
2.66
2.68
85°C
2.66
2.64
2.64
2.62
2.62
2.60
0
1
2
3
4
5
0.06
25°C
85°C
0.04
0.02
0.00
0
SOURCING CURRENT (mA)
1
2
3
4
5
SINKING CURRENT (mA)
Figure 63. Output Voltage vs Sourcing Current
22
85°C
50
Figure 64. Output Voltage vs Sinking Current
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
7 Detailed Description
7.1 Overview
The LMV221 is a versatile logarithmic RF power detector suitable for use in power measurement systems. The
LMV221 is particularly well suited for CDMA and UMTS applications. It produces a DC voltage that is a measure
for the applied RF power.
The core of the LMV221 is a progressive compression LOG detector consisting of four gain stages. Each of
these saturating stages has a gain of approximately 10 dB and therefore achieves about 10 dB of the detector
dynamic range. The five diode cells perform the actual detection and convert the RF signal to a DC current. This
DC current is subsequently supplied to the transimpedance amplifier at the output, which converts it into an
output voltage. In addition, the amplifier provides buffering of and applies filtering to the detector output signal.
To prevent discharge of filtering capacitors between OUT and GND in shutdown, a switch is inserted at the
amplifier input that opens in shutdown to realize a high impedance output of the device.
7.2 Functional Block Diagram
B2 REF
VDD A1
RTRANS
en
en
EN C2
I/I
VREF
RFIN B1
GND C1
V-V
10 dB
10 dB
10 dB
A2 OUT
+
+
-
en
10 dB
RIN
Copyright © 2016, Texas Instruments Incorporated
7.3 Feature Description
7.3.1 Characteristics of the LMV221
The LMV221 is a logarithmic RF power detector with approximately 40-dB dynamic range. This dynamic range
plus its logarithmic behavior make the LMV221 ideal for various applications such as wireless transmit power
control for CDMA and UMTS applications. The frequency range of the LMV221 is from 50 MHz to 3.5 GHz,
which makes it suitable for various applications.
The LMV221 transfer function is accurately temperature compensated. This makes the measurement accurate
for a wide temperature range. Furthermore, the LMV221 can easily be connected to a directional coupler
because of its 50-Ω input termination. The output range is adjustable to fit the ADC input range. The detector can
be switched into a power saving shutdown mode for use in pulsed conditions.
7.3.2 Accurate Power Measurement
The power measurement accuracy achieved with a power detector is not only determined by the accuracy of the
detector itself, but also by the way it is integrated into the application. In many applications some form of
calibration is employed to improve the accuracy of the overall system beyond the intrinsic accuracy provided by
the power detector. For example, for LOG-detectors calibration can be used to eliminate part to part spread of
the LOG-slope and LOG-intercept from the overall power measurement system, thereby improving its power
measurement accuracy.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
23
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Feature Description (continued)
Calibration techniques can be used to improve the accuracy of a power measurement system beyond the
intrinsic accuracy of the power detector itself. LOG-Conformance Error and Temperature Drift Error discuss
power measurement systems using LOG-detectors, specifically the LMV221, but the more generic concepts can
also be applied to other power detectors. Other factors influencing the power measurement accuracy, such as
the resolution of the ADC reading the detector output signal, are not considered here because these factors are
not fundamentally due to the power detector.
7.3.2.1 Concept of Power Measurements
Power measurement systems generally consists of two clearly distinguishable parts with different functions:
1. A power detector device, that generates a DC output signal (voltage) in response to the power level of the
(RF) signal applied to its input.
2. An estimator that converts the measured detector output signal into a (digital) numeric value representing the
power level of the signal at the detector input.
This conceptual configuration is shown in Figure 65.
FEST
MODEL
PIN
FDET
VOUT
PEST
PARAMETERS
Figure 65. Generic Concept of a Power Measurement System
The core of the estimator is usually implemented as a software algorithm, receiving a digitized version of the
detector output voltage. Its transfer FEST from detector output voltage to a numerical output must be equal to the
inverse of the detector transfer FDET from (RF) input power to DC output voltage. If the power measurement
system is ideal, that is, if no errors are introduced into the measurement result by the detector or the estimator,
the measured power PEST(the output of the estimator) and the actual input power PIN must be identical. In that
case, the measurement error E, the difference between the two, should be identically zero:
E = PEST - PIN { 0
œ PEST = FEST[FDET(PIN)] = PIN
-1
œ FEST(VOUT) = FDET(VOUT)
(1)
From Equation 1 it follows that one would design the FEST transfer function to be the inverse of the FDET transfer
function.
In practice the power measurement error is not zero, due to the following effects:
• The detector transfer function is subject to various kinds of random errors that result in uncertainty in the
detector output voltage; the detector transfer function is not exactly known.
• The detector transfer function might be too complicated to be implemented in a practical estimator.
The function of the estimator is then to estimate the input power PIN, that is, to produce an output PEST such that
the power measurement error is, on average, minimized, based on the following information:
1. Measurement of the not-completely-accurate detector output voltage VOUT
2. Knowledge about the detector transfer function FDET, for example the shape of the transfer function, the
types of errors present (part-to-part spread, temperature drift), and so forth.
Obviously the total measurement accuracy can be optimized by minimizing the uncertainty in the detector output
signal (select an accurate power detector), and by incorporating as much accurate information about the detector
transfer function into the estimator as possible.
24
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Feature Description (continued)
The knowledge about the detector transfer function is condensed into a mathematical model for the detector
transfer function, consisting of:
• A formula for the detector transfer function; and
• Values for the parameters in this formula.
The values for the parameters in the model can be obtained in various ways. They can be based on
measurements of the detector transfer function in a precisely controlled environment (parameter extraction). If
the parameter values are separately determined for each individual device, errors like part-to-part spread are
eliminated from the measurement system.
Errors may occur when the operating conditions of the detector (for example, the temperature) become
significantly different from the operating conditions during calibration (for example, room temperature). Examples
of simple estimators for power measurements that result in a number of commonly used metrics for the power
measurement error are discussed in LOG-Conformance Error, Temperature Drift Error, Temperature
Compensation and Temperature Drift Error.
7.3.2.2
LOG-Conformance Error
Probably the simplest power measurement system that can be realized is obtained when the LOG-detector
transfer function is modeled as a perfect linear-in-dB relationship between the input power and output voltage:
VOUT,MOD = FDET,MOD(PIN) = KSLOPE(PIN ± PINTERCEPT)
where
•
KSLOPE represents the LOG-slope and PINTERCEPT the LOG-intercept
(2)
The estimator based on Equation 2 implements the inverse of the model equation, that is:
PEST = FEST(VOUT) =
VOUT
+ PINTERCEPT
KSLOPE
(3)
The resulting power measurement error, the LOG-conformance error, is thus equal to:
ELCE = PEST - PIN =
=
VOUT
- (PIN - PINTERCEPT )
KSLOPE
VOUT - VOUT,MOD
KSLOPE
(4)
The most important contributions to the LOG-conformance error are generally:
• The deviation of the actual detector transfer function from an ideal logarithm (the transfer function is nonlinear
in dB).
• Drift of the detector transfer function over various environmental conditions, most importantly temperature;
KSLOPE and PINTERCEPT are usually determined for room temperature only.
• Part-to-part spread of the (room temperature) transfer function.
The latter component is conveniently removed by means of calibration, that is, if the LOG slope and LOGintercept are determined for each individual detector device (at room temperature). This can be achieved by
measurement of the detector output voltage (at room temperature) for a series of different power levels in the
LOG-linear range of the detector transfer function. The slope and intercept can then be determined by means of
linear regression.
An example of this type of error and its relationship to the detector transfer function is shown in Figure 66.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
25
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
2.0
2.5
1.8
2.0
1.6
1.5
-40°C
VOUT (V)
1.4
1.2
1.0
0.5
25°C
1.0
0.0
85°C
0.8
-0.5
0.6
-1.0
0.4
0.2
0.0
-55
-1.5
85°C
25°C
-2.0
-40°C
-45
LOG CONFORMANCE ERROR (dB)
Feature Description (continued)
-2.5
-35
-25
-15
-5
5
RF INPUT POWER (dBm)
Figure 66. LOG-Conformance Error and LOG-Detector Transfer Function
In the center of the dynamic range of the detector, the LOG-conformance error is small, especially at room
temperature; in this region the transfer function closely follows the linear-in-dB relationship while KSLOPE and
PINTERCEPT are determined based on room temperature measurements. At the temperature extremes the error in
the center of the range is slightly larger due to the temperature drift of the detector transfer function. The error
rapidly increases toward the top and bottom end of the detector's dynamic range; here the detector saturates and
its transfer function starts to deviate significantly from the ideal LOG-linear model. The detector dynamic range is
usually defined as the power range for which the LOG conformance error is smaller than a specified amount.
Often an error of ±1 dB is used as a criterion.
7.3.2.3 Temperature Drift Error
A more accurate power measurement system can be obtained if the first error contribution, due to the deviation
from the ideal LOG-linear model, is eliminated. This is achieved if the actual measured detector transfer function
at room temperature is used as a model for the detector, instead of the ideal LOG-linear transfer function used in
the previous section.
The formula used for such a detector is:
VOUT,MOD = FDET(PIN,TO)
where
•
TO represents the temperature during calibration (room temperature).
(5)
The transfer function of the corresponding estimator is thus the inverse of this:
-1
PEST = FDET[VOUT(T),T0]
where
•
VOUT(T) represents the measured detector output voltage at the operating temperature T.
(6)
The resulting measurement error is only due to drift of the detector transfer function over temperature and can be
expressed as in Equation 7:
-1
EDRIFT (T,T0) = PEST - PIN = FDET[VOUT(T),T0] - PIN
-1
-1
= FDET[VOUT(T),T0] - FDET[VOUT(T),T)]
(7)
26
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Feature Description (continued)
Unfortunately, the (numeric) inverse of the detector transfer function at different temperatures makes this
expression rather impractical. However, because the drift error is usually small VOUT(T) is only slightly different
from VOUT(TO). This means that Equation 8 can be applied:
EDRIFT(T,T0) | EDRIFT(T0,T0)
w
-1
-1
+ (T - T0) w7 {FDET[VOUT(T),T0] - FDET[VOUT(T),T]}
(8)
This expression is easily simplified by taking the following considerations into account:
• The drift error at the calibration temperature E(TO,TO) equals zero (by definition).
• The estimator transfer FDET(VOUT,TO) is not a function of temperature; the estimator output changes over
temperature only due to the temperature dependence of VOUT.
• The actual detector input power PIN is not temperature dependent (in the context of this expression).
• The derivative of the estimator transfer function to VOUT equals approximately 1/KSLOPE in the LOG-linear
region of the detector transfer function (the region of interest).
Taking into account the preceding considerations, the simplified expression would be:
w -1
FDET[VOUT(T),T0]
w7
-1
w VOUT(T)
w
= (T ± T0)
FDET[VOUT(T),T0]
wVOUT
w7
EDRIFT (T,T0) | (T ± T0)
|
VOUT(T) ± VOUT(T0)
KSLOPE
(9)
Equation 9 is very similar to Equation 4 determined previously. The only difference is that instead of the output of
the ideal LOG-linear model, the actual detector output voltage at the calibration temperature is now subtracted
from the detector output voltage at the operating temperature.
Figure 67 depicts an example of the drift error.
TEMPERATURE DRIFT ERROR (dB)
1.5
1.5
1.0
-40°C
1.0
0.5
0.5
0.0
0.0
-0.5
-0.5
-1.0
85°C
-1.5
-1.0
-1.5
-55
-45
-35
-25
-15
-5
5
RF INPUT POWER (dBm)
Figure 67. Temperature Drift Error of the LMV221 at ƒ = 1855 MHz
In agreement with the definition, the temperature drift error is zero at the calibration temperature. Further, the
main difference with the LOG-conformance error is observed at the top and bottom end of the detection range;
instead of a rapid increase the drift error settles to a small value at high and low input power levels due to the
fact that the detector saturation levels are relatively temperature independent.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
27
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Feature Description (continued)
In a practical application it may not be possible to use the exact inverse detector transfer function as the
algorithm for the estimator. For example, it may require too much memory or too much factory calibration time.
However, using the ideal LOG-linear model in combination with a few extra data points at the top and bottom end
of the detection range — where the deviation is largest — can already significantly reduce the power
measurement error.
7.3.2.3.1 Temperature Compensation
A further reduction of the power measurement error is possible if the operating temperature is measured in the
application. For this purpose, the detector model used by the estimator should be extended to cover the
temperature dependency of the detector.
Because the detector transfer function is generally a smooth function of temperature (the output voltage changes
gradually over temperature), the temperature is in most cases adequately modeled by a first-order or secondorder polynomial (see Equation 10).
VOUT,MOD = FDET(PIN,T0)[1 + (T-T0)TC1(PIN)
+ (T-T0)2TC2(PIN) + O(T3)]
(10)
The required temperature dependence of the estimator, to compensate for the detector temperature dependence
can be approximated similarly:
-1
PEST = FDET[VOUT(T),T0]{1 + (T-T0)S1[VOUT(T)] +
+ (T-T0)2S2[VOUT(T)] + O(T3)}
-1
| FDET[VOUT(T),T0]{1 + (T-T0)S1[VOUT(T)]}
(11)
The last approximation results from the fact that a first-order temperature compensation is usually sufficiently
accurate. For second and higher-order compensation a similar approach can be followed.
Ideally, the temperature drift could be completely eliminated if the measurement system is calibrated at various
temperatures and input power levels to determine the temperature sensitivity S1. In a practical application,
however, that is usually not possible due to the associated high costs. The alternative is to use the average
temperature drift in the estimator, instead of the temperature sensitivity of each device individually. In this way it
is possible to eliminate the systematic (reproducible) component of the temperature drift without the need for
calibration at different temperatures during manufacturing. What remains is the random temperature drift, which
differs from device to device. (see Figure 68). The graph at the left of Figure 68 schematically represents the
behavior of the drift error versus temperature at a certain input power level for a large number of devices.
Figure 68. Elimination of the Systematic Component from the Temperature Drift
28
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Feature Description (continued)
The mean drift error represents the reproducible (systematic) part of the error, while the mean ±3 sigma limits
represent the combined systematic plus random error component. Obviously the drift error must be zero at
calibration temperature T0. If the systematic component of the drift error is included in the estimator, the total drift
error becomes equal to only the random component, as shown in the graph at the right of Figure 68. A significant
reduction of the temperature drift error can be achieved in this way only if:
• The systematic component is significantly larger than the random error component (otherwise the difference
is negligible).
• The operating temperature is measured with sufficient accuracy.
It is essential for the effectiveness of the temperature compensation to assign the appropriate value to the
temperature sensitivity S1. Two different methods can be followed to determine this parameter:
1. Determination of a single value to be used over the entire operating temperature range.
2. Division of the operating temperature range in segments and use of separate values for each of the
segments.
For the first method, the accuracy of the extracted temperature sensitivity increases when the number of
measurement temperatures increases. Linear regression to temperature can then be used to determine the two
parameters of the linear model for the temperature drift error: the first order temperature sensitivity S1 and the
best-fit (room temperature) value for the power estimate at T0: FDET[VOUT(T),T0]. Note that to achieve an overall
(over all temperatures) minimum error, the room temperature drift error in the model can be non-zero at the
calibration temperature (which is not in agreement with the strict definition).
The second method does not have this drawback but is more complex. In fact, segmentation of the temperature
range is a form of higher-order temperature compensation using only a first-order model for the different
segments: one for temperatures below 25°C, and one for temperatures above 25°C. The mean (or typical)
temperature sensitivity is the value to be used for compensation of the systematic drift error component.
Figure 69 and Figure 70 show the temperature drift error without and with temperature compensation using two
segments. With compensation the systematic component is completely eliminated; the remaining random error
component is centered around zero. Note that the random component is slightly larger at −40°C than at +85°C.
Figure 69. Temperature Drift Error without Temperature
Compensation
Figure 70. Temperature Drift Error With Temperature
Compensation
In a practical power measurement system, temperature compensation is usually only applied to a small power
range around the maximum power level for two reasons:
1. The various communication standards require the highest accuracy in this range to limit interference.
2. The temperature sensitivity itself is a function of the power level it becomes impractical to store a large
number of different temperature sensitivity values for different power levels.
The 2.7-V DC and AC Electrical Characteristics specifies the temperature sensitivity for the aforementioned two
segments at an input power level of −10 dBm (near the top-end of the detector dynamic range). The typical value
represents the mean which is to be used for calibration.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
29
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Feature Description (continued)
7.3.2.3.2 Differential Power Errors
Many third-generation communication systems contain a power control loop through the base station and mobile
unit that require frequent updates to the transmit-power level by a small amount (typically 1 dB). For such
applications it is important that the actual change of the transmit power is sufficiently close to the requested
power change.
The error metrics in this data sheet that describe the accuracy of the detector for a change in the input power are
E1 dB (for a 1-dB change in the input power) and E10 dB (for a 10-dB step, or ten consecutive steps of 1 dB).
Because it can be assumed that the temperature does not change during the power step the differential error
equals the difference of the drift error at the two involved power levels:
E1dB(PIN,T)= EDRIFT(PIN+1dB,T) - EDRIFT(PIN,T)
E10dB(PIN,T)= EDRIFT(PIN+10dB,T) - EDRIFT(PIN,T)
(12)
NOTE
The step error increases significantly when one (or both) power levels in the above
expression are outside the detector dynamic range. For E10 dB this occurs when PIN is less
than 10 dB below the maximum input power of the dynamic range, PMAX.
7.4 Device Functional Modes
7.4.1 Shutdown
To save power, the LMV221 can be brought into a low power-shutdown mode. The device is active for EN = high
(VEN > 1.1 V) and in the low power-shutdown mode for EN = low (VEN < 0.6 V). In this state the output of the
LMV221 is switched to a high impedance mode. Using the shutdown function, care must be taken not to exceed
the absolute maximum ratings. Forcing a voltage to the enable input that is 400 mV higher than VDD or 400 mV
lower than GND damages the device, and further operation is not ensured. The absolute maximum ratings can
also be exceeded when the enable EN is switched to high (from shutdown to active mode) while the supply
voltage is low (off). This must be prevented at all times. A possible solution to protect the device is to add a
resistor of 100 kΩ in series with the enable input.
7.4.1.1 Output Behavior in Shutdown
In order to save power, the LMV221 can be used in pulsed mode so that it is active to perform the power
measurement only during a fraction of the time. During the remaining time the device is in low-power shutdown.
Applications using this approach usually require that the output value is available at all times, including when the
LMV221 is in shutdown. The settling time in active mode, however, must not become excessively large. This can
be achieved by the combination of the LMV221 and a low pass output filter (see Figure 75).
In active mode, the filter capacitor CS is charged to the output voltage of the LMV221, which in this mode has a
low output impedance to enable fast settling. During shutdown mode, the capacitor should preserve this voltage.
Discharge of CS through any current path must therefore be avoided in shutdown. The output impedance of the
LMV221 becomes high in shutdown, thus, the discharge current cannot flow from the capacitor top plate, through
RS and the device OUT pin to GND. This is detected by the internal shutdown mechanism of the output amplifier
and by the switch depicted in Figure 79. Additionally, the ADC input impedance must be high to prevent a
possible discharge path through the ADC.
30
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
8.1.1 Functionality and Applications of RF Power Detectors
8.1.1.1 Functionality of RF Power Detectors
An RF power detector is a device that produces a DC output voltage in response to the RF power level of the
signal applied to its input. A wide variety of power detectors can be distinguished, each having certain properties
that suit a particular application. This section provides an overview of the key characteristics of power detectors,
and discusses the most important types of power detectors. The functional behavior of the LMV221 is discussed
in detail.
8.1.1.1.1 Key Characteristics of RF Power Detectors
Power detectors are used to accurately measure the power of a signal inside the application. The attainable
accuracy of the measurement is therefore dependent upon the accuracy and predictability of the detector transfer
function from the RF input power to the DC output voltage.
Certain key characteristics determine the accuracy of RF detectors and they are classified accordingly:
• Temperature Stability
• Dynamic Range
• Waveform Dependency
• Transfer Shape
Generally, the transfer function of RF power detectors is slightly temperature dependent. This temperature drift
reduces the accuracy of the power measurement, because most applications are calibrated at room temperature.
In such systems, the temperature drift significantly contributes to the overall system power measurement error.
The temperature stability of the transfer function differs for the various types of power detectors. Generally,
power detectors that contain only one or few semiconductor devices (diodes, transistors) operating at RF
frequencies attain the best temperature stability.
The dynamic range of a power detector is the input power range for which it creates an accurately reproducible
output signal. What is considered accurate is determined by the applied criterion for the detector accuracy; the
detector dynamic range is thus always associated with certain power measurement accuracy. This accuracy is
usually expressed as the deviation of its transfer function from a certain predefined relationship, such as linear in
dB for LOG detectors and square-law transfer (from input RF voltage to DC output voltage) for mean-square
detectors. For LOG-detectors, the dynamic range is often specified as the power range for which its transfer
function follows the ideal linear-in-dB relationship with an error smaller than or equal to ±1 dB. Again, the
attainable dynamic range differs considerably for the various types of power detectors.
According to its definition, the average power is a metric for the average energy content of a signal and is not
directly a function of the shape of the signal in time. In other words, the power contained in a 0-dBm sine wave is
identical to the power contained in a 0-dBm square wave or a 0-dBm WCDMA signal; all these signals have the
same average power. Depending on the internal detection mechanism, though, power detectors may produce a
slightly different output signal in response to the aforementioned waveforms, even though their average power
level is the same. This is due to the fact that not all power detectors strictly implement the definition formula for
signal power, being the mean of the square of the signal. Most types of detectors perform some mixture of peak
detection and average power detection. A waveform independent detector response is often desired in
applications that exhibit a large variety of waveforms, such that separate calibration for each waveform becomes
impractical.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
31
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Application Information (continued)
The shape of the detector transfer function from the RF input power to the DC output voltage determines the
required resolution of the ADC connected to it. The overall power measurement error is the combination of the
error introduced by the detector, and the quantization error contributed by the ADC. The impact of the
quantization error on the overall transfer's accuracy is highly dependent on the detector transfer shape, as shown
in Figure 71 and Figure 72.
2
2
ÂV1
VOUT (V)
VOUT (V)
ÂV
ÂV
ÂV2
0
-60
ÂP
ÂP
RF INPUT POWER (dBm)
0
0
-60
Figure 71. Convex Detector Transfer Function
ÂP
ÂP
RF INPUT POWER (dBm)
0
Figure 72. Linear Transfer Function
Figure 71 and Figure 72 shows two different representations of the detector transfer function. In both Figure 71
and Figure 72 the input power along the horizontal axis is displayed in dBm because most applications specify
power accuracy requirements in dBm (or dB). Figure 71 shows a convex detector transfer function, while the
transfer function on the right hand side is linear (in dB). The slope of the detector transfer function — the detector
conversion gain – is of key importance for the impact of the quantization error on the total measurement error. If
the detector transfer function slope is low, a change, ΔP, in the input power results only in a small change of the
detector output voltage, such that the quantization error is relatively large. On the other hand, if the detector
transfer function slope is high, the output voltage change for the same input power change will be large, such
that the quantization error is small. Figure 72 has a very low slope at low input power levels, resulting in a
relatively large quantization error. Therefore, to achieve accurate power measurement in this region, a highresolution ADC is required. On the other hand, for high input power levels the quantization error are very small
due to the steep slope of the curve in this region. For accurate power measurement in this region, a much lower
ADC resolution is sufficient. Figure 71 has a constant slope over the power range of interest, such that the
required ADC resolution for a certain measurement accuracy is constant. For this reason, the LOG-linear curve
in Figure 71 generally leads to the lowest ADC resolution requirements for certain power measurement accuracy.
32
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Application Information (continued)
8.1.1.1.2 Types of RF Power Detectors
Three different detector types are distinguished based on the four characteristics previously discussed:
• Diode Detector
• (Root) Mean Square (R)MS) Detector
• Logarithmic Detectors
8.1.1.1.2.1 Diode Detector
A diode is one of the simplest types of RF detectors. As depicted in Figure 73, the diode converts the RF input
voltage into a rectified current. This unidirectional current charges the capacitor. The RC time constant of the
resistor and the capacitor determines the amount of filtering applied to the rectified (detected) signal.
Z0
D
VREF
RS
CS
VOUT
Copyright © 2016, Texas Instruments Incorporated
Figure 73. Diode Detector
The advantages and disadvantages can be summarized as follows:
• The temperature stability of the diode detectors is generally very good because they contain only one
semiconductor device that operates at RF frequencies.
• The dynamic range of diode detectors is poor. The conversion gain from the RF input power to the output
voltage quickly drops to very low levels when the input power decreases. Typically a dynamic range of 20 dB
to 25 dB can be achieved with this type of detector.
• The response of diode detectors is waveform dependent. As a consequence of this dependency, for example,
its output voltage for a 0-dBm WCDMA signal is different than for a 0-dBm unmodulated carrier. This is due to
the fact that the diode measures peak power instead of average power. The relation between peak power and
average power is dependent on the wave shape.
• The transfer shape of diode detectors puts high requirements on the resolution of the ADC that reads their
output voltage. Especially at low input power levels a very high ADC resolution is required to achieve
sufficient power measurement accuracy (See Figure 71).
8.1.1.1.2.2 (Root) Mean Square (R)MS) Detector
This type of detector is particularly suited for the power measurements of RF modulated signals that exhibits
large peak-to-average power ratio variations. This is because its operation is based on direct determination of the
average power and not – like the diode detector – of the peak power.
The advantages and disadvantages can be summarized as follows:
• The temperature stability of (R)MS detectors is almost as good as the temperature stability of the diode
detector; only a small part of the circuit operates at RF frequencies, while the rest of the circuit operates at
low frequencies.
• The dynamic range of (R)MS detectors is limited. The lower end of the dynamic range is limited by internal
device offsets.
• The response of (R)MS detectors is highly waveform independent. This is a key advantage compared to other
types of detectors in applications that employ signals with high peak-to-average power variations. For
example, the (R)MS detector response to a 0-dBm WCDMA signal and a 0-dBm unmodulated carrier is
essentially equal.
• The transfer shape of R(MS) detectors has many similarities with the diode detector and is therefore subject
to similar disadvantages with respect to the ADC resolution requirements (see Figure 72).
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
33
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Application Information (continued)
8.1.1.1.2.3 Logarithmic Detectors
The transfer function of a logarithmic detector has a linear in dB response, which means that the output voltage
changes linearly with the RF power in dBm. This is convenient because most communication standards specify
transmit power levels in dBm as well.
The advantages and disadvantages can be summarized as follows:
• The temperature stability of the LOG detector transfer function is generally not as good as the stability of
diode and R(MS) detectors. This is because a significant part of the circuit operates at RF frequencies.
• The dynamic range of LOG detectors is usually much larger than that of other types of detectors.
• Because LOG detectors perform a kind of peak detection their response is wave form dependent, similar to
diode detectors.
• The transfer shape of LOG detectors puts the lowest possible requirements on the ADC resolution (See
Figure 72).
8.2 Typical Applications
RF power detectors can be used in a wide variety of applications. Figure 74 shows the LMV221 in a transmit
power-control system, and Figure 82 measures the voltage standing wave ratio (VSWR).
8.2.1 Application With Transmit Power Control Loop
The key benefit of a transmit power control loop circuit is that it makes the transmit power insensitive to changes
in the power amplifier (PA) gain control function, such as changes due to temperature drift. When a control loop
is used, the transfer function of the PA is eliminated from the overall transfer function. Instead, the overall
transfer function is determined by the power detector. The overall transfer function accuracy depends thus on the
RF detector accuracy. The LMV221 is especially suited for this application, due to the accurate temperature
stability of its transfer function.
Figure 74 shows a block diagram of a typical transmit power control system. The output power of the PA is
measured by the LMV221 through a directional coupler. The measured output voltage of the LMV221 is filtered
and subsequently digitized by the ADC inside the baseband chip. The baseband adjusts the PA output power
level by changing the gain control signal of the RF VGA accordingly. With an input impedance of 50 Ω, the
LMV221 can be directly connected to a 30-dB directional coupler without the need for an additional external
attenuator. The setup can be adjusted to various PA output ranges by selection of a directional coupler with the
appropriate coupling factor.
B
A
S
E
B
A
N
D
RF
COUPLER
PA
VGA
ANTENNA
50 :
GAIN
RS
OUT RFIN
ADC
CS
LOGIC
LMV221
EN
GND
Copyright © 2016, Texas Instruments Incorporated
Figure 74. Transmit Power Control System
34
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Typical Applications (continued)
8.2.1.1 Design Requirements
Some of the design requirements for this logarithmic RMS power detector include:
Table 1. Design Parameters
DESIGN PARAMETER
EXAMPLE VALUE
Supply voltage
2.7 V
RF input frequency (unmodulated continuous wave)
1855 MHz
Minimum input power for ELC = 1 dB
–42.9 dBm
Maximum input power for ELC = 1 dB
–5.5 dBm
Maximum output voltage, PIN = –5 dBm
1.61 V
8.2.1.2 Detailed Design Procedure
8.2.1.2.1 Detector Interfacing
For optimal performance of the LMV221 device, it is important that all its pins are connected to the surrounding
circuitry in the appropriate way. Starting from the Functional Block Diagram the function of each pin is elaborated
in the following sections. The details of the electrical interfacing are separately discussed for each pin. Output
filtering options and the differences between single ended and differential interfacing with an ADC are also
discussed in detail in the following subsections.
8.2.1.2.1.1 RF Input
RF parts typically use a characteristic impedance of 50 Ω. To comply with this standard the LMV221 has an input
impedance of 50 Ω. Using a characteristic impedance other then 50 Ω causes a shift of the logarithmic intercept
with respect to the value given in the 2.7-V DC and AC Electrical Characteristics. This intercept shift can be
calculated according to Equation 13.
2 RSOURCE ·
PINT-SHIFT = 10 LOG §
© RSOURCE + 50¹
(13)
The intercept shifts to higher power levels for RSOURCE > 50 Ω, and shifts to lower power levels for RSOURCE <
50 Ω.
8.2.1.2.1.2 Output and Reference
The possible filtering techniques that can be applied to reduce ripple in the detector output voltage are discussed
in Filtering. In addition, two different topologies to connect the LMV221 to an ADC are elaborated.
8.2.1.2.1.2.1 Filtering
The output voltage of the LMV221 is a measure for the applied RF signal on the RF input pin. Usually, the
applied RF signal contains AM modulation that causes low frequency ripple in the detector output voltage. CDMA
signals, for instance, contain a large amount of amplitude variations. Filtering of the output signal can be used to
eliminate this ripple. The filtering can either be achieved by a low pass output filter or a low pass feedback filter.
Those two techniques are shown in Figure 75 and Figure 76.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
35
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
VDD
VDD
RS
RFIN
2
1
6
RS
OUT
RFIN
+
2
1
6
OUT
+
ADC
EN
4
5
3
ADC
RP
CS
LMV221
REF
CS
LMV221
EN
-
4
5
3
GND
REF
-
GND
Copyright © 2016, Texas Instruments Incorporated
Copyright © 2016, Texas Instruments Incorporated
Figure 75. Low Pass Output Filter
Figure 76. Low Pass Feedback Filter
Depending on the system requirements one of the these filtering techniques can be selected. The low pass
output filter has the advantage that it preserves the output voltage when the LMV221 is brought into shutdown.
This is elaborated in Output Behavior in Shutdown. In the feedback filter, resistor RP discharges capacitor CP in
shutdown and therefore changes the output voltage of the device.
A disadvantage of the low pass output filter is that the series resistor RS limits the output drive capability. This
may cause inaccuracies in the voltage read by an ADC when the ADC input impedance is not significantly larger
than RS. In that case, the current flowing through the ADC input induces an error voltage across filter resistor RS.
The low pass feedback filter does not have this disadvantage.
NOTE
Note that adding an external resistor between OUT and REF reduces the transfer gain
(LOG-slope and LOG-intercept) of the device. The internal feedback resistor sets the gain
of the transimpedance amplifier.
The filtering of the low pass output filter is achieved by resistor RS and capacitor CS. The −3 dB bandwidth of this
filter can then be calculated by: ƒ−3 dB = 1 / 2πRSCS. The bandwidth of the low pass feedback filter is determined
by external resistor RP in parallel with the internal resistor RTRANS, and external capacitor CP in parallel with
internal capacitor CTRANS (see Figure 79). The −3 dB bandwidth of the feedback filter can be calculated by ƒ−3 dB
= 1 / 2π (RP//RTRANS) (CP + CTRANS). The bandwidth set by the internal resistor and capacitor (when no external
components are connected between OUT and REF) equals ƒ−3 dB = 1 / 2π RTRANS CTRANS = 450 kHz.
8.2.1.2.1.3 Interface to the ADC
The LMV221 can be connected to the ADC with a single-ended or a differential topology. The single ended
topology connects the output of the LMV221 to the input of the ADC and the reference pin is not connected. In a
differential topology, both the output and the reference pins of the LMV221 are connected to the ADC. The
topologies are depicted in Figure 77 and Figure 78.
VDD
VDD
RS
RFIN
2
1
6
OUT
RFIN
+
2
1
6
OUT
+
ADC
ADC
RP
LMV221
EN
4
3
5
CP
REF
RP
LMV221
EN
-
GND
4
3
5
REF
CP
-
GND
Copyright © 2016, Texas Instruments Incorporated
Figure 77. Single-Ended Application
Copyright © 2016, Texas Instruments Incorporated
Figure 78. Differential Application
The differential topology has the advantage that it is compensated for temperature drift of the internal reference
voltage. This can be explained by looking at the transimpedance amplifier of the LMV221 (Figure 79).
36
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
REF
CTRANS
RTRANS
IDET
-
VREF
OUT
+
+
-
Copyright © 2016, Texas Instruments Incorporated
Figure 79. Output Stage of the LMV221
Equation 14 shows that the output of the amplifier is set by the detection current IDET multiplied by the resistor
RTRANS plus the reference voltage VREF:
VOUT = IDET RTRANS + VREF
where
•
IDET represents the detector current that is proportional to the RF input power.
(14)
Equation 14 shows that temperature variations in VREF are also present in the output VOUT. In case of a single
ended topology the output is the only pin that is connected to the ADC. The ADC voltage for single ended is
thus:
VADC = IDET RTRANS + VREF
(15)
A differential topology also connects the reference pin, which is the value of reference voltage VREF. The ADC
reads VOUT – VREF:
VADC = VOUT – VREF = IDET RTRANS
(16)
Equation 16 no longer contains the reference voltage VREF anymore. Temperature variations in this reference
voltage are therefore not measured by the ADC.
8.2.1.3 Application Curves
2.0
2.0
1855 MHz
2.0
1.2
1.2
50 MHz
2500 MHz
0.8
0.8
RFIN = -15 dBm
1.2
RFIN = -25 dBm
0.8
RFIN = -35 dBm
3000 MHz
0.4
0.4
0.4
0.0
RFIN = -45 dBm
4000 MHz
0.0
-60
1.6
900 MHz
VOUT (V)
VOUT (V)
1.6
1.6
RFIN = - 5 dBm
-50
-40
-30
-20
-10
0
10
0.0
10M
100M
1G
10G
FREQUENCY (Hz)
RF INPUT POWER (dBm)
Figure 80. Output Voltage vs RF Input Power
Figure 81. Output Voltage vs Frequency
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
37
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
8.2.2 Application With Voltage Standing Wave Ratio (VSWR) Measurement
Transmission in RF systems requires matched termination by the proper characteristic impedance at the
transmitter and receiver side of the link. In wireless transmission systems, however, matched termination of the
antenna can rarely be achieved. The part of the transmitted power that is reflected at the antenna bounces back
toward the PA and may cause standing waves in the transmission line between the PA and the antenna. These
standing waves can attain unacceptable levels that may damage the PA. A VSWR measurement is used to
detect such an occasion. It acts as an alarm function to prevent damage to the transmitter.
VSWR is defined as the ratio of the maximum voltage divided by the minimum voltage at a certain point on the
transmission line:
1+ _*_
VSWR =
1 - _*_
where
•
Γ = VREFLECTED / VFORWARD denotes the reflection coefficient.
(17)
This means that to determine the VSWR, both the forward (transmitted) and the reflected power levels must be
measured. This can be accomplished by using two LMV221 RF power detectors according to Figure 82. A
directional coupler is used to separate the forward and reflected power waves on the transmission line between
the PA and the antenna. One secondary output of the coupler provides a signal proportional to the forward power
wave, the other secondary output provides a signal proportional to the reflected power wave. The outputs of both
RF detectors that measure these signals are connected to a microcontroller or baseband that calculates the
VSWR from the detector output signals.
RF
COUPLER
ANTENNA
PA
MICRO
CONTROLLER
VDD
RFIN
EN
1
2
REVERSE
POWER
6
OUT
ADC1
LMV221
4
3
RP1
5
CP1
REF
GND
RFIN
2
TRANSMITTED
POWER
EN
1
6
OUT
ADC2
LMV221
4
3
5
RP2
CP2
REF
GND
Copyright © 2016, Texas Instruments Incorporated
Figure 82. VSWR Application
9 Power Supply Recommendations
The LMV221 is designed to operate from an input voltage supply range from 2.7 V to 3.3 V. This input voltage
must be well regulated. Enable voltage levels lower than 400 mV below GND could lead to incorrect operation of
the device. Also, the resistance of the input supply rail must be low enough to ensure correct operation of the
device.
38
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
10 Layout
10.1
Layout Guidelines
As with any other RF device, careful attention must be paid to the board layout. If the board layout is not properly
designed, unwanted signals can easily be detected or interference picked up.
Electrical signals (voltages and currents) need a finite time to travel through a trace or transmission line. RF
voltage levels at the generator side and at the detector side can therefore be different. This is not only true for
the RF strip line, but for all traces on the PCB. Signals at different locations or traces on the PCB are in a
different phase of the RF frequency cycle. Phase differences in, for example, the voltage across neighboring
lines, may result in crosstalk between lines due to parasitic capacitive, or inductive coupling. This crosstalk is
further enhanced by the fact that all traces on the PCB are susceptible to resonance. The resonance frequency
depends on the trace geometry. Traces are particularly sensitive to interference when the length of the trace
corresponds to a quarter of the wavelength of the interfering signal or a multiple thereof.
10.1.1 Supply Lines
Because the PSRR of the LMV221 is finite, variations of the supply can result in some variation at the output.
This can be caused among others by RF injection from other parts of the circuitry or the on/off switching of the
PA.
10.1.1.1 Positive Supply (VDD)
In order to minimize the injection of RF interference into the LMV221 through the supply lines, the phase
difference between the PCB traces connecting to VDD and GND must be minimized. A suitable way to achieve
this is to short both connections for RF. This can be done by placing a small decoupling capacitor between the
VDD and GND. It must be placed as close to the device VDD and GND pins as possible as shown in Figure 85.
Be aware that the resonance frequency of the capacitor itself must be above the highest RF frequency used in
the application, because the capacitor acts as an inductor above its resonance frequency.
Low frequency-supply voltage variations due to PA switching might result in a ripple at the output voltage. The
LMV221 has a PSRR of 60 dB for low frequencies.
10.1.1.2 Ground (GND)
The LMV221 must have a ground plane free of noise and other disturbing signals. It is important to separate the
RF ground return path from the other grounds. This is due to the fact that the RF input handles large voltage
swings. A power level of 0 dBm causes a voltage swing larger than 0.6 VPP over the internal 50-Ω input resistor,
resulting in a significant RF return current toward the source. Therefore, TI recommends that the RF ground
return path not be used for other circuits in the design. The RF path must be routed directly back to the source
without loops.
10.1.2 RF Input Interface
The LMV221 is designed to be used in RF applications having a characteristic impedance of 50 Ω. To achieve
this impedance, the input of the LMV221 must be connected via a 50-Ω transmission line. Transmission lines can
be easily created on PCBs using microstrip or (grounded) coplanar waveguide (GCPW) configurations. For more
details about designing microstrip or GCPW transmission lines, TI recommends a microwave designer handbook
is recommended.
10.1.3 Microstrip Configuration
One way to create a transmission line is to use a microstrip configuration. A cross section of the configuration is
shown in Figure 83, assuming a two-layer PCB.
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
39
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
Layout Guidelines (continued)
METAL CONDUCTOR
W
FR4 PCB
H
GROUND PLANE
Figure 83. Microstrip Configuration
A conductor (trace) is placed on the topside of a PCB. The bottom side of the PCB has a fully copper ground
plane. The characteristic impedance of the microstrip transmission line is a function of the width W, height H, and
the dielectric constant εr.
Characteristics such as height and the dielectric constant of the board have significant impact on transmission
line dimensions. A 50-Ω transmission line may result in impractically wide traces. A typical 1.6-mm thick FR4
board results in a trace width of 2.9 mm, for instance. This is impractical for the LMV221 because the pad width
of the 6-pin WSON package is 0.25 mm. The transmission line has to be tapered from 2.9 mm to 0.25 mm.
Significant reflections and resonances in the frequency transfer function of the board may occur due to this
tapering.
10.1.4 GCPW Configuration
A transmission line in a (grounded) coplanar waveguide (GCPW) configuration gives more flexibility in terms of
trace width. The GCPW configuration is constructed with a conductor surrounded by ground at a certain
distance, S, on the top side. Figure 84 shows a cross section of this configuration. The bottom side of the PCB is
a ground plane. The ground planes on both sides of the PCB must be firmly connected to each other by multiple
vias. The characteristic impedance of the transmission line is mainly determined by the width W and the distance
S. In order to minimize reflections, the width W of the center trace must match the size of the package pad. The
required value for the characteristic impedance can subsequently be realized by selection of the proper gap
width S.
METAL CONDUCTOR
S
W
S
H
FR4 PCB
GROUND PLANE
Figure 84. GCPW Configuration
40
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
LMV221
www.ti.com
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
Layout Guidelines (continued)
10.1.5 Reference (REF)
The REF pin can be used to compensate for temperature drift of the internal reference voltage as described in
Interface to the ADC. The REF pin is directly connected to the inverting input of the transimpedance amplifier.
Thus, RF signals and other spurious signals couple directly through to the output. Introduction of RF signals can
be prevented by connecting a small capacitor between the REF pin and ground. The capacitor must be placed
close to the REF pin as depicted in Figure 85.
10.1.6 Output (OUT)
The OUT pin is sensitive to crosstalk from the RF input, especially at high power levels. The ESD diode between
OUT and VDD may rectify the crosstalk, but may add an unwanted inaccurate DC component to the output
voltage.
The board layout must minimize crosstalk between the detectors input RFIN and the output of the detector. Using
an additional capacitor connected between the output and the positive supply voltage (VDD pin) or GND can
prevent this. For optimal performance this capacitor must be placed as close as possible to the OUT pin.
10.2 Layout Example
Figure 85. Recommended LMV221 Board Layout
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
41
LMV221
SNWS018D – DECEMBER 2006 – REVISED JUNE 2016
www.ti.com
11 Device and Documentation Support
11.1 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.2 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.3 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.4 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
42
Submit Documentation Feedback
Copyright © 2006–2016, Texas Instruments Incorporated
Product Folder Links: LMV221
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
LMV221SD/NOPB
ACTIVE
WSON
NGF
6
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
A96
LMV221SDX/NOPB
ACTIVE
WSON
NGF
6
4500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
A96
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
工商网监
湘ICP备2023018690号
