LMV225, LMV226, LMV228
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SNWS013L – AUGUST 2003 – REVISED MARCH 2013
LMV225/LMV226/LMV228 RF Power Detector for CDMA and WCDMA
Check for Samples: LMV225, LMV226, LMV228
FEATURES
DESCRIPTION
•
•
•
•
The LMV225/LMV226/LMV228 are 30 dB RF power
detectors intended for use in CDMA and WCDMA
applications. The device has an RF frequency range
from 450 MHz to 2 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 2.7V to
5.5V. The LMV225/LMV226/LMV228 have an
integrated filter for low-ripple average power detection
of CDMA signals with 30 dB dynamic range.
Additional filtering can be applied using a single
external capacitor.
1
2
•
•
30 dB Linear in dB Power Detection Range
Output Voltage Range 0.2 to 2V
Logic Low Shutdown
Multi-Band Operation from 450 MHz to 2000
MHz
Accurate Temperature Compensation
Packages:
– DSBGA Thin 1.0 mm x 1.0 mm x 0.6 mm
– DSBGA Ultra Thin 1.0 mm x 1.0 mm x 0.35
mm
– WSON 2.2 mm x 2.5 mm x 0.8 mm
– (LMV225 and LMV228)
APPLICATIONS
•
•
•
•
CDMA RF Power Control
WCDMA RF Power Control
CDMA2000 RF Power Control
PA Modules
The LMV225 has an RF power detection range from
–30 dBm to 0 dBm and is ideally suited for direct use
in
combination
with
resistive
taps.
The
LMV226/LMV228 have a detection range from –15
dBm to 15 dBm and are intended for use in
combination with a directional coupler. The LMV226
is equipped with a buffered output which makes it
suitable for GSM, EDGE, GPRS and TDMA
applications.
The device is active for Enable = HI, otherwise it is in
a low power consumption shutdown mode. During
shutdown the output will be LOW. The output voltage
ranges from 0.2V to 2V and can be scaled down to
meet ADC input range requirements.
The LMV225/LMV226/LMV228 power detectors are
offered in the thin 1.0 mm x 1.0 mm x 0.6 mm
DSBGA package and the ultra thin 1.0 mm x 1.0 mm
x 0.35 mm DSBGA package. The LMV225 and the
LMV228 are also offered in the 2.2 mm x 2.5 mm x
0.8 mm WSON package.
Typical Application
RF
ANTENNA
ANTENNA
RF
PA
R1
PA
VDD
1.8 k:
C
100 pF
50:
VDD
LMV225
C
100 pF
RFIN/EN
OUT
R2
ENABLE
RFIN/EN
10 k:
GND
OUT
ENABLE
R2
10 k:
Figure 1. LMV225
LMV226/
LMV228
GND
Figure 2. LMV226/LMV228
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2003–2013, Texas Instruments Incorporated
LMV225, LMV226, LMV228
SNWS013L – AUGUST 2003 – REVISED MARCH 2013
www.ti.com
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.
ABSOLUTE MAXIMUM RATINGS
(1) (2)
Supply Voltage
VDD - GND
ESD Tolerance
6.0V Max
(3)
Human Body Model
2000V
Machine Model
200V
−65°C to 150°C
Storage Temperature Range
Junction Temperature
(4)
150°C Max
Mounting Temperature, Infrared or convection (20 sec)
Tin/Lead
235°C
Lead-Free
260°C
(1)
(2)
(3)
(4)
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is intended to be functional, but specific performance is not specified. For specifications and the test conditions, see
the Electrical Characteristics.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
Human body model: 1.5 kΩ in series with 100 pF. Machine model, 0Ω in series with 100 pF.
The maximum power dissipation is a function of TJ(MAX) , θJA and TA. The maximum allowable power dissipation at any ambient
temperature is PD = (TJ(MAX) - TA)/θJA. All numbers apply for packages soldered directly into a PC board
OPERATING RATINGS
(1)
Supply Voltage
2.7V to 5.5V
−40°C to +85°C
Temperature Range
RF Frequency Range
(1)
2
450 MHz to 2 GHz
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is intended to be functional, but specific performance is not specified. For specifications and the test conditions, see
the Electrical Characteristics.
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SNWS013L – AUGUST 2003 – REVISED MARCH 2013
2.7 DC AND AC ELECTRICAL CHARACTERISTICS
Unless otherwise specified, all limits are specified to VDD = 2.7V; TJ = 25°C. Boldface limits apply at temperature extremes.
Symbol
IDD
Parameter
Condition
Supply Current
Active Mode: RFIN/EN = VDD
(DC), No RF Input Power
Present
Min
Typ
Max
LMV225
4.8
7
8
LMV226
4.9
6.2
8
LMV228
4.9
6.2
8
0.44
4.5
μA
0.8
V
Shutdown: RFIN/EN = GND (DC), No RF Input
Power Present
VLOW
EN Logic Low Input Level
VHIGH
EN Logic High Input Level
ton
Turn-on-Time
tr
IEN
PIN
(2)
Rise Time
(3)
No RF Input Power Present,
Output Loaded with 10 pF
(4)
LMV225
2.1
LMV226
1.2
LMV228
1.7
Step from no Power to
0 dBm Applied, Output
Loaded with 10 pF
LMV225
4.5
Step from no Power to
15 dBm Applied, Output
Loaded with 10 pF
LMV226
1.8
LMV228
4.8
LMV225
LMV226
LMV228
(1)
(2)
(3)
(4)
(5)
μs
μs
1
(5)
mA
V
Current into RFIN/EN Pin
Input Power Range
Units
1.8
(2)
(1)
μA
−30
0
dBm
−43
−13
dBV
−15
15
dBm
−28
2
dBV
−15
15
dBm
−28
2
dBV
Electrical Table 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 specified by design or statistical analysis
Turn-on time is measured by connecting a 10 kΩ resistor to the RFIN/EN pin. Be aware that in the actual application on the front page,
the RC-time constant of resistor R2 and capacitor C adds an additional delay.
Typical values represent the most likely parametric norm.
Power in dBV = dBm + 13 when the impedance is 50Ω.
Copyright © 2003–2013, Texas Instruments Incorporated
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2.7 DC AND AC ELECTRICAL CHARACTERISTICS (continued)
Unless otherwise specified, all limits are specified to VDD = 2.7V; TJ = 25°C. Boldface limits apply at temperature extremes. (1)
Symbol
Parameter
Logarithmic Slope
Condition
(6)
900 MHz
1800 MHz
1900 MHz
2000 MHz
Logarithmic Intercept
(6)
900 MHz
1800 MHz
1900 MHz
2000 MHz
VOUT
Output Voltage
No RF Input Power Present
Min
LMV225
44.0
LMV226
44.5
LMV228
DSBGA
44.0
LMV228 WSON
48.5
LMV225
39.4
LMV226
41.6
LMV228
DSBGA
41.9
LMV228 WSON
47.4
LMV225
38.5
LMV226
41.2
LMV228
DSBGA
41.6
LMV228 WSON
46.6
LMV225
38.5
LMV226
41.0
LMV228
DSBGA
41.2
45.4
−45.5
LMV226
−24.5
LMV228
DSBGA
−27.2
LMV228 WSON
−23.7
LMV225
−46.6
LMV226
−25.1
LMV228
DSBGA
−28.2
LMV228 WSON
−23.8
LMV225
−46.3
LMV226
−24.9
LMV228
DSBGA
−28.0
LMV228 WSON
−23.7
LMV225
−46.7
LMV226
−24.7
LMV228
DSBGA
−28.0
LMV228 WSON
-23.6
LMV225
214
350
LMV226
223
350
228
350
LMV228
LMV226 Only
4.5
ROUT
Output Impedance
LMV225/LMV228 only, no RF Input Power
Present
Units
mV/dB
LMV225
Output Current Sourcing/Sinking
4
Max
LMV228 WSON
IOUT
(6)
Typ
dBm
5.3
19.8
mV
mA
29
34
kΩ
Device is set in active mode with a 10 kΩ resistor from VDD to RFIN/EN. RF signal is applied using a 50Ω RF signal generator AC
coupled to the RFIN/EN pin using a 100 pF coupling capacitor.
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SNWS013L – AUGUST 2003 – REVISED MARCH 2013
2.7 DC AND AC ELECTRICAL CHARACTERISTICS (continued)
Unless otherwise specified, all limits are specified to VDD = 2.7V; TJ = 25°C. Boldface limits apply at temperature extremes. (1)
Symbol
en
Parameter
Condition
Min
RF Input = 1800 MHz, −10 dBm for LMV225
and 5 dBm for LMV226/LMV228, Measured at
10 kHz
Output Referred Noise
Variation Due to Temperature
Typ
nV/√Hz
LMV225
+0.64
−1.07
900 MHz, RFIN = 15 dBm
Referred to 25°C
LMV226
+0.05
−0.02
LMV228
DSBGA
+0.22
−0.36
LMV228 WSON
+0.87
−0.87
1800 MHz, RFIN = 0 dBm
Referred to 25°C
LMV225
+0.09
−0.86
1800 MHz, RFIN = 15 dBm
Referred to 25°C
LMV226
+0.07
−0.10
LMV228
DSBGA
+0.29
−0.57
LMV228 WSON
+1.04
−1.23
1900 MHz, RFIN = 0 dBm
Referred to 25°C
LMV225
+0
−0.69
1900 MHz, RFIN = 15 dBm
Referred to 25°C
LMV226
+0
−0.10
LMV228
DSBGA
+0.23
−0.64
LMV228 WSON
+1.05
−1.45
2000 MHz, RFIN = 0 dBm
Referred to 25°C
LMV225
+0
−0.86
2000 MHz, RFIN = 15 dBm
Referred to 25°C
LMV226
+0
−0.29
LMV228
DSBGA
+0.27
−0.65
LMV228 WSON
+1.04
−2.02
Product Folder Links: LMV225 LMV226 LMV228
Units
700
900 MHz, RFIN = 0 dBm
Referred to 25°C
Copyright © 2003–2013, Texas Instruments Incorporated
Max
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5
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SNWS013L – AUGUST 2003 – REVISED MARCH 2013
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5.0 DC AND AC ELECTRICAL CHARACTERISTICS
Unless otherwise specified, all limits are specified to VDD = 5.0V; TJ = 25°C. Boldface limits apply at temperature extremes.
Symbol
IDD
Parameter
Supply Current
Condition
Active Mode: RFIN/EN = VDD
(DC), no RF Input Power
Present.
Min
Typ
Max
LMV225
5.3
7.5
9
LMV226
5.3
6.8
9
LMV228
5.4
6.8
9
0.32
4.5
μA
0.8
V
Shutdown: RFIN/EN = GND (DC), no RF Input
Power Present.
VLOW
EN Logic Low Input Level
VHIGH
EN Logic High Input Level
ton
Turn-on-Time
tr
IEN
PIN
(2)
1.8
(2)
Rise Time
(3)
No RF Input Power Present,
Output Loaded with 10 pF
(4)
Input Power Range
LMV225
2.1
LMV226
1.0
LMV228
1.7
Step from no Power to
0 dBm Applied, Output
Loaded with 10 pF
LMV225
4.5
Step from no Power to
15 dBm Applied, Output
Loaded with 10 pF
LMV226
1.4
LMV228
4.8
LMV226
LMV228
(1)
(2)
(3)
(4)
(5)
6
mA
μs
μs
1
LMV225
Units
V
Current Into RFIN/EN Pin
(5)
(1)
μA
−30
0
dBm
−43
−13
dBV
−15
15
dBm
−28
2
dBV
−15
15
dBm
−28
2
dBV
Electrical Table 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 specified by design or statistical analysis
Turn-on time is measured by connecting a 10 kΩ resistor to the RFIN/EN pin. Be aware that in the actual application on the front page,
the RC-time constant of resistor R2 and capacitor C adds an additional delay.
Typical values represent the most likely parametric norm.
Power in dBV = dBm + 13 when the impedance is 50Ω.
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SNWS013L – AUGUST 2003 – REVISED MARCH 2013
5.0 DC AND AC ELECTRICAL CHARACTERISTICS (continued)
Unless otherwise specified, all limits are specified to VDD = 5.0V; TJ = 25°C. Boldface limits apply at temperature extremes. (1)
Symbol
Parameter
Logarithmic Slope
Condition
(6)
900 MHz
1800 MHz
1900 MHz
2000 MHz
Logarithmic Intercept
(6)
900 MHz
1800 MHz
1900 MHz
2000 MHz
VOUT
Output Voltage
No RF Input Power Present
Min
LMV225
44.6
LMV226
44.6
LMV228
DSBGA
44.2
LMV228 WSON
48.4
LMV225
40.6
LMV226
42.2
LMV228
DSBGA
42.4
LMV228 WSON
48.3
LMV225
39.6
LMV226
41.8
LMV228
DSBGA
42.2
LMV228 WSON
47.8
LMV225
39.7
LMV226
41.6
LMV228
DSBGA
41.8
LMV228 WSON
47.2
LMV225
−47.0
LMV226
−25.0
LMV228
DSBGA
−27.7
LMV228 WSON
−23.9
LMV225
−48.5
LMV226
−25.7
LMV228
DSBGA
−28.9
LMV228 WSON
−23.6
LMV225
−48.2
LMV226
−25.6
LMV228
DSBGA
−28.7
LMV228 WSON
−23.1
LMV225
−48.9
LMV226
−25.5
LMV228
DSBGA
−28.7
LMV228 WSON
−23.0
Output Current Sourcing/Sinking
LMV226 Only
ROUT
Output Impedance
No RF Input Power Present
(6)
Max
dBm
222
400
LMV226
231
400
244
400
4.5
Units
mV/dB
LMV225
LMV228
IOUT
Typ
5.3
23.7
mV
mA
29
31
kΩ
Device is set in active mode with a 10 kΩ resistor from VDD to RFIN/EN. RF signal is applied using a 50Ω RF signal generator AC
coupled to the RFIN/EN pin using a 100 pF coupling capacitor.
Copyright © 2003–2013, Texas Instruments Incorporated
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5.0 DC AND AC ELECTRICAL CHARACTERISTICS (continued)
Unless otherwise specified, all limits are specified to VDD = 5.0V; TJ = 25°C. Boldface limits apply at temperature extremes. (1)
Symbol
en
8
Parameter
Condition
Min
Typ
Output Referred Noise
RF Input = 1800 MHz, −10 dBm for LMV225
and 5 dBm for LMV226/LMV228, Measured at
10 kHz
Variation Due to Temperature
900 MHz, RFIN = 0 dBm
Referred to 25°C
LMV225
+0.89
−1.16
900 MHz, RFIN = 15 dBm
Referred to 25°C
LMV226
+0.25
−0.16
LMV228
DSBGA
+0.46
−0.62
LMV228 WSON
+1.39
−1.19
1800 MHz, RFIN = 0 dBm
Referred to 25°C
LMV225
+0.3
−0.82
1800 MHz, RFIN = 15 dBm
Referred to 25°C
LMV226
+0.21
−0.09
LMV228
DSBGA
+0.55
−0.78
LMV228 WSON
+1.39
−1.43
1900 MHz, RFIN = 0 dBm
Referred to 25°C
LMV225
+0.34
−0.63
1900 MHz, RFIN = 15 dBm
Referred to 25°C
LMV226
+0.21
−0.19
LMV228
DSBGA
+0.55
−0.93
LMV228 WSON
+1.54
−1.64
2000 MHz, RFIN = 0 dBm
Referred to 25°C
LMV225
+0.22
−0.75
2000 MHz RFIN = 15 dBm
Referred to 25°C
LMV226
+0.25
−0.34
LMV228
DSBGA
+0.61−
0.91
LMV228 WSON
+0.89
−0.99
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700
Max
Units
nV/√Hz
dB
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SNWS013L – AUGUST 2003 – REVISED MARCH 2013
CONNECTION DIAGRAM
GND
RFIN/EN
A1
A2
6 OUT
1
VDD
NC 2
1.0mm
GND
B1
B2
5 NC
RFIN/EN 3
4
VDD
OUT
1.0mm
500Pm
300Pm
125Pm
BUMP PITCH
BUMP DIAMETER
SOLDER DOT DIAMETER/
PASSIVATION OPENING
Figure 3. 4-Bump DSBGA – Top View
See Package Number YZR0004 or YPD0004
Figure 4. 6-pin WSON – Top View
See Package Number NGF0006A
PIN DESCRIPTIONS
Pin
Power Supply
Output
Name
Description
DSBGA
WSON6
A2
4
VDD
Positive Supply Voltage
B1
1
GND
Power Ground
A1
3
RFIN/EN
DC voltage determines enable state of the device (HIGH =
device active). AC voltage is the RF input signal to the
detector (beyond 450 MHz). The RFIN/EN pin is internally
terminated with 50Ω in series with 45 pF.
B2
6
Out
Ground referenced detector output voltage (linear in dBm)
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Block Diagrams
VDD
LOGIC
ENABLE
DETECTOR
OUT
I/I
RFIN/EN
10 dB
10 dB
10 dB
GND
Figure 5. LMV225
VDD
LOGIC
ENABLE
+
-
I/I
OUT
RFIN/EN
10 dB
10 dB
10 dB
GND
Figure 6. LMV226
10
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SNWS013L – AUGUST 2003 – REVISED MARCH 2013
VDD
LOGIC
ENABLE
I/I
OUT
RFIN/EN
10 dB
10 dB
10 dB
GND
Figure 7. LMV228
Copyright © 2003–2013, Texas Instruments Incorporated
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TYPICAL PERFORMANCE CHARACTERISTICS LMV225
Unless otherwise specified, VDD = 2.7V, TJ = 25°C.
Supply Current
vs.
Supply Voltage (LMV225)
Output Voltage
vs.
RF Input Power (LMV225)
2.50
8
2.25
900MHz
2.00
85°C
7
1800MHz
1.75
2000MHz
6.5
6
VOUT (V)
SUPPLY CURRENT (mA)
7.5
25°C
5.5
1.50
1900MHz
1.25
1.00
0.75
5
0.50
-40°C
4.5
0.25
4
2.5
3
3.5
4
4.5
0.00
-50
5
-40
0
10
20
Output Voltage and Log Conformance vs.
RF Input Power @ 900 MHz (LMV225)
Output Voltage and Log Conformance vs.
RF Input Power @ 1800 MHz (LMV225)
2.50
2.50
2.25
3
2.00
2
1.75
1.75
-40°C
1.50
1
1.25
0
-40°C
-1
85°C
4
3
25°C
2
1.50
1
-40°C
1.25
0
-40°C
1.00
-1
0.75
-2
0.75
-2
0.50
-3
0.50
-3
0.25
-4
0.25
-4
0.00
-50
-5
0.00
-50
-5
-40
-30
-20
-10
0
10
20
-40
RF INPUT POWER (dBm)
-30
Figure 10.
25°C
2.00
25°C
1.50
-40°C
4
2.25
3
2.00
2
1.75
1
1.25
1.00
2.50
0
-1
-40°C
VOUT (V)
85°C
1.75
0
10
20
Output Voltage and Log Conformance vs.
RF Input Power @ 2000 MHz (LMV225)
5
ERROR (dB)
2.50
85°C
-10
Figure 11.
Output Voltage and Log Conformance
vs.
RF Input Power @ 1900 MHz (LMV225)
2.25
-20
RF INPUT POWER (dBm)
5
25°C
85°C
4
85°C
3
25°C
2
1.50
-40°C
1
1.25
0
1.00
-1
-40°C
0.75
-2
0.75
-2
0.50
-3
0.50
-3
0.25
-4
0.25
-4
0.00
-50
-5
0.00
-50
-5
-40
-30
-20
-10
0
10
20
-40
RF INPUT POWER (dBm)
-20
-10
0
10
20
RF INPUT POWER (dBm)
Figure 12.
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-30
ERROR (dB)
1.00
VOUT (V)
25°C
5
85°C
25°C
ERROR (dB)
5
4
25°C
ERROR (dB)
85°C
2.00
VOUT (V)
-10
Figure 9.
85°C
12
-20
Figure 8.
2.25
VOUT (V)
-30
RF INPUT POWER (dBm)
SUPPLY VOLTAGE (V)
Figure 13.
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SNWS013L – AUGUST 2003 – REVISED MARCH 2013
TYPICAL PERFORMANCE CHARACTERISTICS LMV225
(continued)
Unless otherwise specified, VDD = 2.7V, TJ = 25°C.
Logarithmic Slope vs. Frequency (LMV225)
Logarithmic Intercept vs. Frequency (LMV225)
47
-43
46
-40°C
-44
44
INTERCEPT (dBm)
SLOPE (mV/dB)
45
25°C
43
42
41
85°C
40
-40°C
-45
25°C
-46
-47
39
38
85°C
37
400
800
1200
1600
-48
400
2000
800
1200
1600
2000
FREQUENCY (MHz)
FREQUENCY (MHz)
Figure 14.
Figure 15.
Output Variation vs. RF Input Power
Normalized to 25°C @ 900 MHz (LMV225)
Output Variation vs. RF Input Power
Normalized to 25°C @ 1800 MHz (LMV225)
1.5
1.5
85°C
1.0
85°C
0.5
ERROR (dB)
ERROR (dB)
1.0
0.0
-0.5
0.5
0.0
-0.5
-40°C
-1.0
-1.0
-1.5
-1.5
-40°C
-50
-40
-30
-20
-10
0
10
-50
20
-40
-30
-20
-10
0
10
20
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 16.
Figure 17.
Output Variation vs. RF Input Power
Normalized to 25°C @ 1900 MHz (LMV225)
Output Variation vs. RF Input Power
Normalized to 25°C @ 2000 MHz (LMV225)
1.5
1.5
85°C
1.0
1.0
0.5
0.5
ERROR (dB)
ERROR (dB)
85°C
0.0
-0.5
-1.0
0.0
-0.5
-1.0
-40°C
-40°C
-1.5
-1.5
-50
-40
-30
-20
-10
0
10
20
-50
RF INPUT POWER (dBm)
Figure 18.
-40
-30
-20
-10
0
10
20
RF INPUT POWER (dBm)
Figure 19.
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TYPICAL PERFORMANCE CHARACTERISTICS LMV225
(continued)
Unless otherwise specified, VDD = 2.7V, TJ = 25°C.
PSRR vs.Frequency
(LMV225 in DSBGA)
70
PSRR vs. Frequency
(LMV225 in WSON)
5V
60
PSRR (dB)
50
40
2.7V
30
20
10
0
100
1k
10k
100k
1M
FREQUENCY (Hz)
Figure 20.
Figure 21.
RF Input Impedance vs. Frequency @ Resistance and
Reactance (LMV225 in DSBGA)
RF Input Impedance vs. Frequency @ Resistance and
Reactance (LMV225 in WSON)
150
100
IMPEDANCE (:)
R
50
0
X
-50
-100
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
FREQUENCY (GHz)
Figure 22.
Figure 23.
TYPICAL PERFORMANCE CHARACTERISTICS LMV226
Unless otherwise specified, VDD = 2.7V, TJ= 25°C.
Output Voltage vs. RF Input Power (LMV226)
7.0
2.50
6.5
2.25
6.0
2.00
900 MHz
1800 MHz
85°C
1.75
5.5
VOUT (V)
SUPPLY CURRENT (mA)
Supply Current vs. Supply Voltage (LMV226)
5.0
25°C
4.5
4.0
1.50
1.00
2000 MHz
0.75
-40°C
3.5
0.50
3.0
0.25
2.5
2.5
3
3.5
4
4.5
5
0.00
-50
SUPPLY VOLTAGE (V)
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-40
-30
-20
-10
0
10
20
RF INPUT POWER (dBm)
Figure 24.
14
1900 MHz
1.25
Figure 25.
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TYPICAL PERFORMANCE CHARACTERISTICS LMV226
(continued)
Unless otherwise specified, VDD = 2.7V, TJ= 25°C.
Output Voltage and Log Conformance vs.
RF Input Power @ 900 MHz (LMV226)
Output Voltage and Log Conformance vs. RF Input Power
@ 1800 MHz (LMV226)
2.50
5
2.50
2.25
4
2.25
3
2.00
2
1.75
85°C
2.00
5
4
85°C
85°C
25°C
0
1.25
-40°C
1.00
-1
0.75
2
-40°C
25°C
1
1.50
0
1.25
-40°C
1.00
-1
-2
0.75
-2
0.50
-3
0.50
-3
0.25
-4
0.25
-4
-5
0.00
-50
0.00
-50
-40
-30
-20
-10
10
0
20
ERROR (dB)
VOUT (V)
1
VOUT (V)
-40°C
25°C
ERROR (dB)
85°C
1.50
3
25°C
1.75
-5
-40
RF INPUT POWER (dBm)
-30
-20
-10
0
10
20
RF INPUT POWER (dBm)
Figure 26.
Figure 27.
Output Voltage and Log Conformance vs. RF Input Power
@ 1900 MHz (LMV226)
Output Voltage and Log Conformance vs. RF Input Power
@ 2000 MHz (LMV226)
2.50
5
2.50
2.25
4
2.25
3
2.00
2
1.75
85°C
85°C
25°C
VOUT (V)
3
1
0
1.25
-40°C
2
-40°C
25°C
1.50
1
0
1.25
-40°C
1.00
-1
-2
0.75
-2
0.50
-3
0.50
-3
0.25
-4
0.25
-4
-5
0.00
-50
1.00
-1
0.75
0.00
-50
-40
-30
-20
-10
0
10
20
ERROR (dB)
-40°C
VOUT (V)
25°C
1.50
4
85°C
85°C
25°C
1.75
ERROR (dB)
2.00
5
-5
-40
-30
-20
-10
0
10
20
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 28.
Figure 29.
Logarithmic Slope vs. Frequency (LMV226)
Logarithmic Intercept vs. Frequency (LMV226)
-23.0
46
25°C
45
-23.5
44
-24.0
INTERCEPT (dBm)
SLOPE (mV/dB)
-40°C
43
85°C
42
41
-40°C
25°C
-24.5
-25.0
-25.5
85°C
-26.0
40
39
400
800
1200
1600
2000
-26.5
400
800
1200
1600
FREQUENCY (MHz)
FREQUENCY (MHz)
Figure 30.
Figure 31.
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TYPICAL PERFORMANCE CHARACTERISTICS LMV226
(continued)
Unless otherwise specified, VDD = 2.7V, TJ= 25°C.
Output Variation vs. RF Input Power
Normalized to 25°C @ 900 MHz (LMV226)
Output Variation vs. RF Input Power
Normalized to 25°C @ 1800 MHz (LMV226)
1.5
1.5
1.0
1.0
85°C
ERROR (dB)
ERROR (dB)
85°C
0.5
0.5
0.0
-0.5
-40°C
0.0
-0.5
-40°C
-1.0
-1.5
-50
-1.0
-30
-40
-20
-10
0
10
-1.5
-50
20
-40
-30
-20
-10
0
10
20
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 32.
Figure 33.
Output Variation vs. RF Input Power
Normalized to 25°C @ 1900 MHz (LMV226)
Output Variation vs. RF Input Power
Normalized to 25°C @ 2000 MHz (LMV226)
1.5
1.5
1.0
85°C
1.0
85°C
0.5
ERROR (dB)
ERROR (dB)
0.5
0.0
-0.5
0.0
-0.5
-40°C
-1.0
-1.5
-50
-40°C
-1.0
-40
-30
-20
-10
0
10
-1.5
-50
20
-40
RF INPUT POWER (dBm)
70
-30
-20
-10
0
10
20
RF INPUT POWER (dBm)
Figure 34.
Figure 35.
PSRR vs. Frequency
(LMV226)
RF Input Impedance vs. Frequency @ Resistance and
Reactance (LMV226)
150
5V
60
100
R
IMPEDANCE (:)
PSRR (dB)
50
40
2.7V
30
20
50
0
X
-50
10
0
100
1k
10k
100k
1M
-100
0.4
Figure 36.
16
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0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
FREQUENCY (GHz)
FREQUENCY (Hz)
Figure 37.
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TYPICAL PERFORMANCE CHARACTERISTICS LMV228 IN DSBGA
Unless otherwise specified, VDD = 2.7V, TJ= 25°C.
Supply Current vs. Supply Voltage
(LMV228 in DSBGA)
Output Voltage vs. RF Input Power
(LMV228 in DSBGA)
7.0
2.50
6.5
2.25
1800 MHz
85°C
1.75
5.5
1900 MHz
VOUT (V)
SUPPLY CURRENT (mA)
900 MHz
2.00
6.0
5.0
25°C
4.5
1.50
1.25
2000 MHz
1.00
4.0
0.75
3.5
-40°C
0.50
3.0
0.25
2.5
2.5
3
3.5
4
4.5
0.00
-50
5
-40
-30
SUPPLY VOLTAGE (V)
-20
-10
0
10
20
RF INPUT POWER (dBm)
Figure 38.
Figure 39.
Output Voltage and Log Conformance vs.
RF Input Power @ 900 MHz (LMV228 in DSBGA)
Output Voltage and Log Conformance vs.
RF Input Power @ 1800 MHz (LMV228 in DSBGA)
2.50
85°C
2.25
25°C
2.00
5
2.50
4
2.25
3
2.00
2
1.75
5
85°C
4
25°C
3
0
1.25
-40°C
1.00
-1
0.75
2
-40°C
25°C
1.50
1.25
1
0
-40°C
1.00
-1
-2
0.75
-2
0.50
-3
0.50
-3
0.25
-4
0.25
-4
-5
0.00
-50
0.00
-50
-40
-30
-20
-10
0
10
20
ERROR (dB)
VOUT (V)
1
25°C
VOUT (V)
-40°C
85°C
1.50
ERROR (dB)
85°C
1.75
-5
-40
-30
-20
-10
0
10
20
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 40.
Figure 41.
Output Voltage and Log Conformance vs.
RF Input Power @ 1900 MHz (LMV228 in DSBGA)
Output Voltage and Log Conformance vs.
RF Input Power @ 2000 MHz (LMV228 in DSBGA)
2.50
85°C
2.25
25°C
2.00
5
2.50
4
2.25
3
2.00
2
1.75
5
85°C
0
-40°C
1.00
-1
0.75
2
-40°C
1.50
1
25°C
0
1.25
-40°C
1.00
-1
-2
0.75
-2
0.50
-3
0.50
-3
0.25
-4
0.25
-4
-5
0.00
-50
0.00
-50
-40
-30
-20
-10
0
10
20
ERROR (dB)
1
VOUT (V)
VOUT (V)
-40°C
25°C
1.25
3
85°C
ERROR (dB)
85°C
1.75
1.50
4
25°C
-5
-40
RF INPUT POWER (dBm)
Figure 42.
-30
-20
-10
0
10
20
RF INPUT POWER (dBm)
Figure 43.
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TYPICAL PERFORMANCE CHARACTERISTICS LMV228 IN DSBGA
(continued)
Unless otherwise specified, VDD = 2.7V, TJ= 25°C.
Logarithmic Slope vs.
Frequency (LMV228 in DSBGA)
Logarithmic Intercept vs.
Frequency (LMV228 in DSBGA)
44.5
-25.5
-40°C
25°C
44.0
-26.0
-40°C
INTERCEPT (dBm)
SLOPE (mV/dB)
43.5
43.0
85°C
42.5
42.0
41.5
-26.5
25°C
-27.0
-27.5
-28.0
85°C
-28.5
41.0
40.5
400
800
1200
1600
-29.0
400
2000
800
1200
1600
2000
FREQUENCY (MHz)
FREQUENCY (MHz)
Figure 44.
Figure 45.
Output Variation vs.
RF Input Power Normalized to 25°C @ 900 MHz (LMV228 in
DSBGA)
Output Variation vs.
RF Input Power Normalized to 25°C @ 1800 MHz (LMV228 in
DSBGA)
1.5
1.5
1.0
1.0
85°C
85°C
0.5
ERROR (dB)
ERROR (dB)
0.5
0.0
-0.5
-40°C
0.0
-0.5
-40°C
-1.0
-1.0
-1.5
-50
-40
-30
-20
-10
0
10
-1.5
-50
20
-30
-20
-10
0
10
20
RF INPUT POWER (dBm)
Figure 46.
Figure 47.
Output Variation vs.
RF Input Power Normalized to 25°C @ 1900 MHz (LMV228 in
DSBGA)
Output Variation vs.
RF Input Power Normalized to 25°C @ 2000 MHz (LMV228 in
DSBGA)
1.5
1.5
1.0
1.0
85°C
0.0
-0.5
-40°C
-1.0
-1.5
-50
85°C
0.5
ERROR (dB)
ERROR (dB)
0.5
18
-40
RF INPUT POWER (dBm)
-40
-30
-20
-10
0
0.0
-0.5
-1.0
10
20
-1.5
-50
-40°C
-40
-30
-20
-10
0
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 48.
Figure 49.
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TYPICAL PERFORMANCE CHARACTERISTICS LMV228 IN DSBGA
(continued)
Unless otherwise specified, VDD = 2.7V, TJ= 25°C.
PSRR vs. Frequency
(LMV228 in DSBGA)
70
RF Input Impedance vs. Frequency @ Resistance and
Reactance (LMV228 in DSBGA)
150
5V
60
100
R
IMPEDANCE (:)
PSRR (dB)
50
40
2.7V
30
20
50
0
X
-50
10
-100
0.4
0
100
1k
10k
100k
1M
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
FREQUENCY (GHz)
FREQUENCY (Hz)
Figure 50.
Figure 51.
TYPICAL PERFORMANCE CHARACTERISTICS LMV228 IN WSON
Unless otherwise specified, VDD = 2.7V, TJ= 25°C.
Supply Current
vs.
Supply Voltage (LMV228 in WSON)
Output Voltage
vs.
RF Input Power (LMV228 in WSON)
7.0
SUPPLY CURRENT (mA)
6.5
6.0
85°C
5.5
5.0
25°C
4.5
4.0
3.5
-40°C
3.0
2.5
2.5
3
3.5
4
4.5
5
SUPPLY VOLTAGE (V)
Figure 52.
Figure 53.
Output Voltage and Log Conformance
vs.
RF Input Power @ 900 MHz (LMV228 inWSON)
Output Voltage and Log Conformance vs.
RF Input Power @ 1800 MHz (LMV228 in WSON)
1.80
3
1.60
1.40
2
1.40
1.20
1
1.00
0
VOUT (V)
1.60
85°C
25°C
0.80
-1
-40°C
0.60
-40°C
25°C
0.20
0.00
-50
-40
-30
4
85°C
3
2
1.20
1
25°C
1.00
-2
0.60
-3
0.40
-4
0.20
0
-40°C
0.80
-1
-2
85°C
85°C
0.40
5
ERROR (dB)
2.00
4
VOUT (V)
5
1.80
ERROR (dB)
2.00
-20
-10
0
10
-5
20
0.00
-50
-3
-40°C
-4
25°C
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 54.
Figure 55.
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TYPICAL PERFORMANCE CHARACTERISTICS LMV228 IN WSON
(continued)
Unless otherwise specified, VDD = 2.7V, TJ= 25°C.
2.00
5
4
1.80
4
3
1.60
1.40
2
1.40
2
1.20
1
1.20
1
85°C
VOUT (V)
25°C
1.00
0
-40°C
0.80
-1
0.60
-40°C
0.20
0.00
-50
25°C
-40
-30
1.00
0.60
-3
0.40
-4
0.20
0
25°C
0.80
-2
3
85°C
-1
-40°C
-2
85°C
85°C
0.40
VOUT (V)
5
1.80
ERROR (dB)
2.00
1.60
20
Output Voltage and Log Conformance vs.
RF Input Power @ 2000 MHz (LMV228 in WSON)
ERROR (dB)
Output Voltage and Log Conformance
vs.
RF Input Power @ 1900 MHz (LMV228 in WSON)
-20
-10
0
10
-5
20
0.00
-50
-3
-40°C
-4
25°C
-40
-30
-20
-10
0
10
-5
20
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 56.
Figure 57.
Logarithmic Slope
vs.
Frequency (LMV228 in WSON)
Logarithmic Intercept
vs.
Frequency (LMV228 in WSON)
Figure 58.
Figure 59.
Output Variation
vs.
RF Input Power Normalized to 25°C @ 900 MHz (LMV228 in
WSON)
Output Variation
vs.
RF Input Power Normalized to 25°C @ 1800 MHz (LMV228 in
WSON)
Figure 60.
Figure 61.
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TYPICAL PERFORMANCE CHARACTERISTICS LMV228 IN WSON
(continued)
Unless otherwise specified, VDD = 2.7V, TJ= 25°C.
Output Variation
vs.
RF Input Power Normalized to 25°C @ 1900 MHz (LMV228 in
WSON)
Output Variation
vs.
RF Input Power Normalized to 25°C @ 2000 MHz (LMV228 in
WSON)
Figure 62.
Figure 63.
PSRR
vs.
Frequency
(LMV228 in WSON)
RF Input Impedance
vs.
Frequency @ Resistance and Reactance (LMV228 in WSON)
Figure 64.
Figure 65.
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APPLICATION NOTES
CONFIGURING A TYPICAL APPLICATION
The LMV225/LMV226/LMV228 are power detectors intended for CDMA and WCDMA applications. Power
applied at its input translates to a DC voltage on the output through a linear-in-dB response. The LMV225
detector is especially suited for power measurements via a high-resistive tap, while the LMV226/LMV228 are
designed to be used in combination with a directional coupler. The LMV226 has an additional output voltage
buffer and therefore a low output impedance. The key features of the devices are shown in .
Table 1. DEVICE CHARACTERISTICS
Input Range (dBm)
Output Buffer
LMV225
−30 / 0
No
High Resistive Tap
Application
LMV226
−15 / 15
Yes
Directional Coupler
LMV228
−15 / 15
No
Directional Coupler
In order to match the output power range of the power amplifier (PA) with the range of the LMV225’s input, the
high resistive tap needs to be configured correctly. In case of the LMV226/LMV228 the coupling factor of the
directional coupler needs to be chosen correctly.
HIGH RESISTIVE TAP APPLICATION
The constant input impedance of the device enables the realization of a frequency independent input attenuation
to adjust the LMV225’s range to the range of the PA. Resistor R1 and the 50Ω input resistance (RIN) of the
device realize this attenuation (Figure 66). To minimize insertion loss, resistor R1 needs to be sufficiently large.
The following example demonstrates how to determine the proper value for R1.
RF
ANTENNA
PA
R1
1.8 k:
C
100 pF
VDD
RFIN/EN
LMV225
RIN
ENABLE
R2
10 k:
OUT
CIN
GND
Figure 66. Typical LMV225 Application with High Resistive Tap
Suppose the useful output power of the PA ranges up to +31 dBm. As the LMV225 can handle input power
levels up to 0 dBm. R1 should realize a minimum attenuation of 31 - 0 = 31 dB. The attenuation realized by R1
and the effective input resistance RIN of the detector equals:
AdB = 20·LOG 1 +
R1
= 31dB
RIN
(1)
Solving this expression for R1, using that RIN = 50Ω, yields:
AdB
31
R1 = 10 20 -1 · RIN = 10 20 -1 · 50 = 1724:
(2)
In Figure 66, R1 is set to 1800Ω resulting in an attenuation of 31.4 dB.
22
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DIRECTIONAL COUPLER APPLICATION
The LMV226/LMV228 also has a 50Ω input resistance. However, its input range differs compared to the
LMV225, i.e. −15 dBm to +15 dBm. If a typical attenuation of a directional coupler is 20 dB, the LMV226/LMV228
can be directly connected via the directional coupler to the PA without the need of additional external attenuator
(Figure 67). Different PA ranges can be configured using couplers with other coupling factors.
ANTENNA
RF
PA
50:
VDD
C
100 pF
RFIN/EN
LMV226/
LMV228
OUT
ENABLE
R2
10 k:
GND
Figure 67. Typical LMV226/LMV228 Application with
Directional Coupler
SHUTDOWN FUNCTIONALITY
The LMV225/LMV226/LMV228 RFIN/EN pins have 2 functions combined:
• Enable/Shutdown
• Power input
The capacitor C and the resistor R2 (Figure 66 and Figure 67) separate the DC shutdown functionality from the
AC power measurement. The device is active when Enable = HI, otherwise it is in a low power consumption
shutdown mode. During shutdown the output will be LOW.
Capacitor C should be chosen sufficiently large to ensure a corner frequency far below the lowest input
frequency to be measured. In case of the LMV225 the corner frequency can be calculated using:
1
f=
C · CIN
2 S (R1 + RIN)
C + CIN
where
•
RIN = 50Ω, CIN = 45 pF typical
(3)
With R1 = 1800Ω and C = 100 pF, this results in a corner frequency of 2.8 MHz. This corner frequency is an
indicative number. The goal is to have a magnitude transfer, which is sufficiently flat in the used frequency range;
capacitor C should be chosen significantly larger than capacitor CIN to assure a proper performance of the high
resistive tap. Capacitor C shouldn’t be chosen excessively large since the RC-time, it introduces in combination
with resistor R2, adds to the turn-on time of the device.
The LMV226/LMV228 do not use a resistor R1 like the LMV225. Though a resistor is seen on the coupler side
(RCOUPLER). Therefore a similar equation holds for the LMV226/LMV228 LF corner frequency, where R1 is
replaced with the coupler output impedance (RCOUPLER).
With RCOUPLER = 50Ω and C = 100 pF, the resulting corner frequency is 50 MHz.
The output voltage is proportional to the logarithm of the input power, often called “linear-in-dB”. Figure 68 shows
the typical output voltage versus PA output power of the LMV225 setup as depicted in Figure 66.
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LMV225 OUTPUT VOLTAGE (V)
2.25
2.00 LMV225
RF INPUT POWER
1.75
31.4 dB
1.50
1.25
1.00
0.75
0.50
PA OUTPUT
POWER
0.25
0.00
-50 -40 -30 -20 -10
0
10
20
30
40
POWER (dBm)
Figure 68. Typical power detector response, VOUT vs. PA output Power
OUTPUT RIPPLE DUE TO AM MODULATION
A CDMA modulated carrier wave generally contains some amplitude modulation that might disturb the RF power
measurement used for controlling the PA. This section explains the relation between amplitude modulation in the
RF signal and the ripple on the output of the LMV225/LMV228. Expressions are provided to estimate this ripple
on the output. The ripple can be further reduced by lowpass filtering at the output. This is realized by connecting
an capacitor from the output of the LMV225/LMV228 to ground.
Estimating Output Ripple
The CDMA modulated RF input signal of Figure 68 can be described as:
VIN(t) = VIN [1 + μ(t)] cos (2 · π · f · t)
where
•
•
VIN is the amplitude of the carrier frequency
Amplitude modulation μ(t) can be between -1 and 1
(4)
VIN (1 + P
VIN
VIN (1 - P
0
Figure 69. AM Modulated RF Signal
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The ripple observed at the output of the detector equals the detectors response to the power variation at the
input due to AM modulation (Figure 69). This signal has a maximum amplitude VIN • (1+μ) and a minimum
amplitude VIN • (1-μ), where 1+μ can be maximum 2 and 1-μ can be minimum 0. The amplitude of the ripple can
be described with the formula:
2
2
VIN (1 + P)2
VRIPPLE = VY
VIN (1 - P)2
+30 -VY
10 LOG
2RIN
+30
10 LOG
2RIN
PINMIN IN dBm
PINMAX IN dBm
where
•
•
VY is the slope of the detection curve (Figure 70)
μ is the modulation index
(5)
Equation 5 can be reduced to:
VRIPPLE = VY · 20 LOG
1+P
1-P
(6)
Consequently, the ripple is independent of the average input power of the RF input signal and only depends on
the logarithmic slope VY and the ratio of the maximum and the minimum input signal amplitude.
For CDMA, the ratio of the maximum and the minimum input signal amplitude modulation is typically in the order
of 5 to 6 dB, which is equivalent to a modulation index μ of 0.28 to 0.33.
A further understanding of the equation above can be achieved via the knowledge that the output voltage VOUT of
the LMV225/LMV228 is linear in dB, or proportional to the input power PIN in dBm. As discussed earlier, CDMA
has a modulation in the order of 5 to 6 dB. Since the transfer is linear in dB, the output voltage VOUT will vary
linearly over about 5 to 6 dB in the curve (Figure 70).
VOUT (V)
200mV
SLOPE = VY
5dB
PZ
PIN (dBm)
Figure 70. VOUT vs. RF Input Power PIN
The output voltage variation ΔVOUT is thus identical for RF input signals that fall within the linear range (in dB) of
the detector. In other words, the output variation is independent of the absolute RF input signal:
ΔVO = VY · ΔPIN
(7)
In which VYis the slope of the curve. The log-conformance error is usually much smaller than the ripple due to
AM modulation. In case of the LMV225/LMV228, VY = 40 mV/dB. With ΔPIN = 5 dB for CDMA, ΔVOUT = 200
mVPP. This is valid for all VOUT.
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Output Ripple with Additional Filtering
The calculated result above is for an unfiltered configuration. When a low pass filter is used by shunting a
capacitor of e.g. COUT = 1.5 nF at the output of the LMV225/LMV228 to ground, this ripple is further attenuated.
The cut-off frequency follows from:
fC =
1
2 S COUT RO
(8)
With the output resistance of the LMV225/LMV228 RO = 19.8 kΩ typical and COUT = 1.5 nF, the cut-off frequency
equals fC = 5.36 kHz. A 100 kHz AM signal then gets attenuated by 5.36/100 or 25.4 dB. The remaining ripple
will be less than 20 mV. With a slope of 40 mV/dB this translates into an error of less than ±0.5 dB. Since the
LMV226 has a low output impedance buffer, a capacitor to reduce the ripple will not be effective.
Output Ripple Measurement
Figure 71 shows the ripple reduction that can be achieved by adding additional capacitance at the output of the
LMV225/LMV228. The RF signal of 900 MHz is AM modulated with a 100 kHz sinewave and a modulation index
of 0.3. The RF input power is swept while the modulation index remains unchanged. Without the output capacitor
the ripple is about 200 mVPP. Connecting a capacitor of 1.5 nF at the output to ground, results in a ripple of 12
mVPP. The attenuation with a 1.5 nF capacitor is then 20 • log (200/12) = 24.4 dB. This is very close to the
calculated number of the previous paragraph.
1000
OUTPUT RIPPLE (mVPP)
NO ADDITIONAL CAPACITOR
100
10
COUT = 1.5nF
1
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
Figure 71. Output Ripple vs. RF Input Power
PRINCIPLE OF OPERATION
The logarithmic response of the LMV225/LMV226/LMV228 is implemented by a logarithmic amplifier as shown in
Figure 72. The logarithmic amplifier consists of a number of cascaded linear gain cells. With these gain cells, a
piecewise approximation of the logarithmic function is constructed.
+
+
+
+
Y
A/0
X0
A/0
X1
A/0
X2
A/0
X3
X4
Figure 72. Logarithmic Amplifier
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Every gain cell has a response according to Figure 73. At a certain threshold (EK), the gain cell starts to saturate,
which means that the gain drops to zero. The output of gain cell 1 is connected to the input of gain cell 2 and so
on.
y
x0
xA
A/0
x
y
x
EK
Figure 73. Gain Cell
All gain cell outputs are AM-demodulated with a peak detector and summed together. This results in a
logarithmic function. The logarithmic range is about:
20 · n · log (A)
where
•
•
n = number of gain cells
A = gain per gaincell
(9)
Figure 74 shows a logarithmic function on a linear scale and the piecewise approximation of the logarithmic
function.
Y
Y = LOG (X)
3
EK/A
EK/A
EK/A
1
X (LIN)
EK
2
Figure 74. Log-Function on Lin Scale
Figure 75 shows a logarithmic function on a logarithmic scale and the piecewise approximation of the logarithmic
function.
Y
Y=X
Y = AX
2
Y=A X
3
Y=A X
EK/A3
EK/A2
EK/A1
EK
X (Log)
Figure 75. Log-Function on Log Scale
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The maximum error for this approximation occurs at the geometric mean of a gain section, which is e.g. for the
third segment:
EK
A
2 ·
EK
A
1 =
EK
A A
(10)
The size of the error increases with distance between the thresholds.
LAYOUT CONSIDERATIONS
For a proper functioning part a good board layout is necessary. Special care should be taken for the series
resistance R1 (Figure 66) that determines the attenuation. For high resistor values the parasitic capacitance of
the resistor may significantly impact the realized attenuation. The effective attenuation will be lower than
intended. To reduce the parasitic capacitance across resistor R1, this resistor can be composed of several
components in series instead of using a single component.
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SNWS013L – AUGUST 2003 – REVISED MARCH 2013
REVISION HISTORY
Changes from Revision K (March 2013) to Revision L
•
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 28
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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)
LMV225SD/NOPB
ACTIVE
WSON
NGF
6
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
A90
LMV225SDX/NOPB
NRND
WSON
NGF
6
4500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
A90
LMV225TL/NOPB
ACTIVE
DSBGA
YZR
4
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
LMV225TLX/NOPB
ACTIVE
DSBGA
YZR
4
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
LMV225UR/NOPB
ACTIVE
DSBGA
YPD
4
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
LMV225URX/NOPB
ACTIVE
DSBGA
YPD
4
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
LMV226TL/NOPB
ACTIVE
DSBGA
YZR
4
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
LMV226TLX/NOPB
ACTIVE
DSBGA
YZR
4
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
LMV226UR/NOPB
ACTIVE
DSBGA
YPD
4
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
LMV228SD/NOPB
ACTIVE
WSON
NGF
6
1000
RoHS & Green
SN
Level-1-260C-UNLIM
LMV228TL/NOPB
ACTIVE
DSBGA
YZR
4
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
LMV228TLX/NOPB
ACTIVE
DSBGA
YZR
4
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
A89
(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
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