LTC5540
600MHz to 1.3GHz
High Dynamic Range
Downconverting Mixer
Description
Features
n
n
n
n
n
n
n
n
n
n
n
n
n
n
Conversion Gain: 7.9dB at 900MHz
IIP3: 25.9dBm at 900MHz
Noise Figure: 9.9dB at 900MHz
16.2dB NF Under +5dBm Blocking
High Input P1dB
3.3V Supply, 640mW Power Consumption
Shutdown Pin
50Ω Single-Ended RF and LO Inputs
LO Inputs 50Ω Matched when Shutdown
High Isolation LO Switch
0dBm LO Drive Level
High LO-RF and LO-IF Isolation
Small Solution Size
20-Lead (5mm × 5mm) QFN package
The LTC®5540 is part of a family of high dynamic range, high
gain passive downconverting mixers covering the 600MHz
to 4GHz frequency range. The LTC5540 is optimized for
0.6GHz to 1.3GHz RF applications. The LO frequency
must fall within the 0.7GHz to 1.2GHz range for optimum
performance. A typical application is a LTE or GSM receiver
with a 700MHz to 915MHz RF input and high-side LO.
The LTC5540 is designed for 3.3V operation, however; the
IF amplifier can be powered by 5V for the highest P1dB.
An integrated SPDT LO switch with fast switching accepts
two active LO signals, while providing high isolation.
The LTC5540’s high conversion gain and high dynamic
range enable the use of lossy IF filters in high-selectivity
receiver designs, while minimizing the total solution cost,
board space and system-level variation.
Applications
Wireless Infrastructure Receivers
(LTE, GSM, W-CDMA)
n Point-to-Point Microwave links
n High Dynamic Range Downmixer Applications
High Dynamic Range Downconverting Mixer Family
n
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
PART#
RF RANGE
LO RANGE
LTC5540
600MHz –1.3GHz
700MHz – 1.2GHz
LTC5541
1.3GHz – 2.3GHz
1.4GHz – 2.0GHz
LTC5542
1.6GHz – 2.7GHz
1.7GHz – 2.5GHz
LTC5543
2.3GHz – 4GHz
2.4GHz – 3.6GHz
Typical Application
Wideband Receiver
190MHz
SAW
VCCIF
3.3V or 5V
1µF
22pF
1.5pF
5.6pF
LNA
IF+
IF –
LTC5540
IF
100pF
SYNTH 2
ALTERNATE LO FOR
FREQUENCY-HOPPING
LO
100pF
BIAS
SHDN
VCC2
VCC 3.3V
LO2
RF
IMAGE
BPF
SHDN
(0V/3.3V)
ADC
1µF
VCC1
22pF
VCC3
LO1
LOSEL
LO SELECT
(0V/3.3V)
16
28
15
27
14
26
13
12
11
LO
1090MHz
5540 TA01
25
IIP3
24
23
10
22
9
8
SYNTH 1
NF
TA = +25°C
fIF = 190MHz
fLO = fRF + fIF
21
20
GC
7
6
600
IIP3 (dBm)
RF
700MHz
TO
915MHz
CT
IF
AMP
1nF
150nH
150nH
Wideband Conversion Gain, IIP3
and NF vs RF Input Frequency
190MHz
BPF
GC (dB), NF (dB)
1nF
19
800
700
900
RF FREQUENCY (MHz)
18
1000
5540 TA01a
5540f
LTC5540
Absolute Maximum Ratings
Pin Configuration
(Note 1)
IFGND
GND
IF–
IFBIAS
IF+
TOP VIEW
Mixer Supply Voltage (VCC1, VCC2)...........................3.8V
LO Switch Supply Voltage (VCC3).............................3.8V
IF Supply Voltage (IF+, IF –).......................................5.5V
Shutdown Voltage (SHDN).................–0.3V to VCC +0.3V
LO Select Voltage (LOSEL).................–0.3V to VCC +0.3V
LO1, LO2 Input Power (0.2GHz to 2GHz)................9dBm
LO1, LO2 Input DC Voltage.....................................±0.5V
RF Input Power (0.2GHz to 2GHz).........................15dBm
RF Input DC Voltage................................................ ±0.1V
Operating Temperature Range..................–40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
Junction Temperature (TJ)..................................... 150°C
20 19 18 17 16
15 LO2
NC 1
RF 2
14 VCC3
21
GND
CT 3
GND 4
13 GND
12 GND
11 LO1
8
VCC2
VCC1
9 10
GND
7
LOSEL
6
LOBIAS
SHDN 5
UH PACKAGE
20-LEAD (5mm s 5mm) PLASTIC QFN
TJMAX = 150°C, θJA = 34°C/W, θJC = 3°C/W
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC5540IUH#PBF
LTC5540IUH#TRPBF
5540
20-Lead (5mm × 5mm) Plastic QFN
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
AC Electrical Characteristics
VCC = 3.3V, VCCIF = 3.3V, SHDN = Low, TA = 25°C, PLO = 0dBm,
unless otherwise noted. Test circuit shown in Figure 1. (Notes 2, 3, 4)
PARAMETER
CONDITIONS
MIN
LO Input Frequency Range
TYP
MAX
UNITS
700 to 1200
MHz
800 to 1300
600 to 1100
MHz
MHz
5 to 500
MHz
RF Input Frequency Range
Low-Side LO
High-Side LO
IF Output Frequency Range
Requires External Matching
RF Input Return Loss
ZO = 50Ω, 600MHz to 1300MHz
>12
dB
LO Input Return Loss
ZO = 50Ω, 700MHz to 1200MHz
>12
dB
IF Output Return Loss
Requires External Matching
>12
dB
LO Input Power
fLO = 700MHz to 1200MHz
–4
0
6
dBm
LO to RF Leakage
fLO = 700MHz to 1200MHz
47
dB
dB
RF to LO Isolation
fRF = 600MHz to 1300MHz
>55
dB
RF to IF Isolation
fRF = 600MHz to 1300MHz
>37
dB
5540f
LTC5540
AC Electrical Characteristics
VCC = 3.3V, VCCIF = 3.3V, SHDN = Low, TA = 25°C, PLO = 0dBm,
PRF = –3dBm (∆f = 2MHz for two-tone IIP3 tests),unless otherwise noted. Test circuit shown in Figure 1. (Notes 2, 3, 4)
High-Side LO Downmixer Application: RF = 600MHz to 1100MHz, IF = 190MHz, fLO = fRF +fIF
PARAMETER
CONDITIONS
Conversion Gain
RF = 700MHz
RF = 900MHz
RF = 1100MHz
MIN
TYP
6.3
7.6
7.9
7.9
MAX
UNITS
dB
dB
dB
Conversion Gain Flatness
RF = 900 ±30MHz, LO = 1090MHz, IF=190 ±30MHz
±0.20
dB
Conversion Gain vs Temperature
TA = –40ºC to +85ºC, RF = 900MHz
–0.008
dB/°C
Input 3rd Order Intercept
RF = 700MHz
RF = 900MHz
RF = 1100MHz
26.5
25.9
23.8
dBm
dBm
dBm
SSB Noise Figure
RF = 700MHz
RF = 900MHz
RF = 1100MHz
10.0
9.9
10.4
SSB Noise Figure Under Blocking
fRF = 900MHz, fLO = 1090MHz,
fBLOCK = 800MHz, PBLOCK = 5dBm
16.2
dB
2LO – 2RF Output Spurious Product
(fRF = fLO – fIF/2)
fRF = 995MHz at –10dBm, fLO = 1090MHz, fIF = 190MHz
–70
dBc
3LO – 3RF Output Spurious Product
(fRF = fLO – fIF/3)
fRF = 1026.67MHz at –10dBm, fLO = 1090MHz, fIF = 190MHz
–75
dBc
Input 1dB Compression
RF = 900MHz, VCCIF = 3.3V
RF = 900MHz, VCCIF = 5V
11
14.5
dBm
dBm
23.4
11.7
dB
dB
dB
Low-Side LO Downmixer Application: RF = 800MHz-1300MHz, IF = 190MHz, fLO = fRF –fIF
PARAMETER
CONDITIONS
Conversion Gain
RF = 900MHz
RF = 1100MHz
RF = 1300MHz
MIN
TYP
7.0
7.8
8.0
MAX
UNITS
dB
dB
dB
Conversion Gain Flatness
RF = 900MHz ±30MHz, LO = 710MHz, IF = 190 ±30MHz
±0.33
dB
Conversion Gain vs Temperature
TA = –40°C to 85°C, RF = 900MHz
–0.007
dB/°C
Input 3rd Order Intercept
RF = 900MHz
RF = 1100MHz
RF = 1300MHz
24.4
24.1
23.6
dBm
dBm
dBm
SSB Noise Figure
RF = 900MHz
RF = 1100MHz
RF = 1300MHz
10.6
10.5
10.3
dB
dB
dB
SSB Noise Figure Under Blocking
fRF = 900MHz, fLO = 710MHz, fIF = 190MHz,
fBLOCK = 1000MHz, PBLOCK = 5dBm
16.7
dB
2RF – 2LO Output Spurious Product
(fRF = fLO + fIF/2)
fRF = 805MHz at –10dBm, fLO = 710MHz,
fIF = 190MHz
–61.5
dBc
3RF – 3LO Output Spurious Product
(fRF = fLO + fIF/3)
fRF = 773.33MHz at –10dBm, fLO = 710MHz,
fIF = 190MHz
–68
dBc
Input 1dB Compression
RF = 900MHz, VCCIF = 3.3V
RF = 900MHz, VCCIF = 5V
11
14
dBm
dBm
5540f
LTC5540
DC Electrical Characteristics
noted. Test circuit shown in Figure 1. (Note 2)
PARAMETER
VCC = 3.3V, VCCIF = 3.3V, SHDN = Low, TA = 25°C, unless otherwise
CONDITIONS
MIN
TYP
MAX
UNITS
VCC Supply Voltage (Pins 6, 8 and 14)
3.1
3.3
3.5
VCCIF Supply Voltage (Pins 18 and 19)
3.1
3.3
5.3
V
97
96
193
116
120
236
mA
mA
mA
500
µA
Power Supply Requirements (VCC, VCCIF)
VCC Supply Current (Pins 6 + 8 + 14)
VCCIF Supply Current (Pins 18 + 19)
Total Supply Current (VCC + VCCIF)
Total Supply Current – Shutdown
SHDN = High
V
Shutdown Logic Input (SHDN) Low = On, High = Off
SHDN Input High Voltage (Off)
3
V
SHDN Input Low Voltage (On)
–0.3V to VCC + 0.3V
SHDN Input Current
–20
0.3
V
30
µA
Turn On Time
1
µs
Turn Off Time
1.5
µs
LO Select Logic Input (LOSEL) Low = LO1 Selected, High = LO2 Selected
LOSEL Input High Voltage
3
V
LOSEL Input Low Voltage
–0.3V to VCC + 0.3V
LOSEL Input Current
–20
LO Switching Time
Typical DC Performance Characteristics
VCC Supply Current
vs Supply Voltage
(Mixer and LO Switch)
90
110
90
70
85
3.3
3.2
3.4
3.5
VCC SUPPLY VOLTAGE (V)
3.6
5540 G01
50
3.0
220
210
SUPPLY CURRENT (mA)
95
ns
Total Supply Current
vs Temperature (VCC + VCCIF)
85°C
25°C
–40°C
130
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
150
85°C
25°C
–40°C
3.1
µA
SHDN = Low, Test circuit shown in Figure 1.
VCCIF Supply Current
vs Supply Voltage (IF Amplifier)
100
80
3.0
30
Note 3: SSB Noise Figure measured with a small-signal noise source,
bandpass filter and 6dB matching pad on RF input, bandpass filter and
6dB matching pad on the LO input, and no other RF signals applied.
Note 4: LO switch isolation is measured at the IF output port at the IF
frequency with fLO1 and fLO2 offset by 2MHz.
105
V
50
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC5540 is guaranteed functional over the operating
temperature range from –40°C to 85°C.
110
0.3
200
VCC = 3.3V, VCCIF = 5V
(DUAL SUPPLY)
190
VCC = VCCIF = 3.3V
(SINGLE SUPPLY)
180
170
3.3
3.6 3.9 4.2 4.5 4.8 5.1
VCCIF SUPPLY VOLTAGE (V)
5.4
5540 G02
160
–45
–25
–5
15
55
35
TEMPERATURE (°C)
75
95
5540 G03
5540f
LTC5540
Typical
AC Performance Characteristics
High-Side LO
VCC = 3.3V, VCCIF = 3.3V, SHDN = Low, TA = 25°C, PLO = 0dBm, PRF = –3dBm (–3dBm/tone for two-tone IIP3 tests, ∆f = 2MHz),
IF = 190MHz, unless otherwise noted. Test circuit shown in Figure 1.
Conversion Gain, IIP3 and NF
vs RF Frequency
LO Leakage vs LO Frequency
RF Isolation vs RF Frequency
22
26
20
IIP3
16
10
20
14
8
NF
12
–20
LO LEAKAGE (dBm)
18
85°C 16
25°C
14
–40°C
12
22
6
10
6
600
55
LO-RF
–30
–40
–60
700
0
1100
800
900
1000
RF FREQUENCY (MHz)
RF-IF
35
30
800
900
1000
1100
LO FREQUENCY (MHz)
25
600
1200
700
800 900 1000 1100 1200 1300
RF FREQUENCY (MHz)
5540 G05
700MHz Conversion Gain, IIP3
and NF vs LO Input Power
5540 G06
900MHz Conversion Gain, IIP3
and NF vs LO Input Power
1100MHz Conversion Gain, IIP3
and NF vs LO Input Power
28
20
26
18
24
18
24
18
22
16
20
85°C 16
25°C
–40°C 14
22
20
85°C 16
25°C
–40°C 14
20
14
18
12
18
12
18
12
16
10
16
10
16
10
14
8
14
8
IIP3
22
10
6
GC
8
6
–6
–4
–2
0
2
4
LO INPUT POWER (dBm)
6
NF
12
4
10
2
8
0
6
6
GC
–6
–4
–2
0
2
4
LO INPUT POWER (dBm)
5540 G07
6
22
14
4
10
2
8
0
6
GC
–6
26
24
18
24
18
85°C 16
25°C
–40°C 14
22
18
12
16
10
14
8
NF
12
10
8
6
3.0
6
GC
3.2
3.3
3.1
3.4
3.5
VCC , VCCIF SUPPLY VOLTAGE (V)
3.6
5540 G10
20
18
RF = 900MHz
VCC = 3.3V
85°C 16
25°C
–40°C 14
12
16
10
14
8
NF
12
4
10
2
8
0
6
3.0
6
4
GC
4
4.5
3.5
5
VCCIF SUPPLY VOLTAGE (V)
5.5
5540 G11
GC (dB), IIP3 (dBm), P1dB (dBm)
28
20
GC (dB), IIP3 (dBm)
22
26
SSB NF (dB)
28
20
SSB NF (dB)
22
RF = 900MHz
VCC = VCCIF
–2
0
2
4
LO INPUT POWER (dBm)
6
0
900MHz Conversion Gain, IIP3
and RF Input P1dB vs Temperature
26
20
4
5540 G09
Conversion Gain, IIP3 and NF
vs IF Supply Voltage (Dual Supply)
IIP3
6
2
–4
28
IIP3
8
NF
85°C
25°C
–40°C
12
5540 G08
Conversion Gain, IIP3 and NF
vs Supply Voltage (Single Supply)
22
20
IIP3
SSB NF (dB)
NF
12
IIP3
GC (dB), IIP3 (dBm)
22
26
GC (dB), IIP3 (dBm)
28
20
SSB NF (dB)
22
26
SSB NF (dB)
28
24
GC (dB), IIP3 (dBm)
40
LO-IF
5540 G04
GC (dB), IIP3 (dBm)
45
2
700
RF-LO
50
–50
4
GC
8
65
60
18
SSB NF (dB)
GC (dB), IIP3 (dBm)
24
–10
ISOLATION (dB)
28
24
RF = 900MHz
VCCIF = 5.0V
VCCIF = 3.3V
IIP3
22
20
18
16
14
P1dB
12
10
2
8
0
6
–45
GC
–25
–5 15
35 55
TEMPERATURE (°C)
75
95
5540 G12
5540f
LTC5540
Typical AC Performance Characteristics
High-Side LO (continued)
VCC = 3.3V, VCCIF = 3.3V, SHDN = Low, TA = 25°C, PLO = 0dBm, PRF = –3dBm (–3dBm/tone for two-tone IIP3 tests, ∆f = 2MHz),
IF = 190MHz, unless otherwise noted. Test circuit shown in Figure 1.
Single-Tone IF Output Power, 2 × 2
and 3 × 3 Spurs vs RF Input Power
20
10
10
0
–10
–20 RF1 = 899 MHz
–30 RF2 = 901MHz
LO = 1090MHz
–40
–50
–60
LO = 1090MHz
IFOUT
RF = 900MHz
–10
–20
3LO–3RF
RF = 1026.67MHz
–30
–40
–50
2LO–2RF
RF = 995MHz
–60
IM3
IM5
–70
–80
–12
–55
0
IFOUT
–9
–6
–3
0
3
RF INPUT POWER (dBm/TONE)
–80
–12
6
–9
–6
–3
0
3
RF INPUT POWER (dBm)
–75
3LO–3RF
RF = 1026.67MHz
–80
14
55
LO2 SELECTED
50
6
fRF = 850MHz TO 950MHz
fLO = 1090MHz
9
LO1 SELECTED
GAIN (dB)
16
–3
0
3
LO INPUT POWER (dBm)
Wideband Conversion Gain
vs IF Frequency
10
60
18
–6
5540 G15
65
ISOLATION (dB)
SSB NF (dBm)
–70
–85
6
70
8
7
45
12
10
8
–20
–15
–10
–5
0
5
RF BLOCKER POWER (dBm)
6
40
RF = 900MHz
BLOCKER = 800MHz
35
700
10
800
900 1000 1100 1200
LO FREQUENCY (MHz)
900MHz Conversion
Gain Distribution
35
35
90°C
25°C
–45°C
30
30
25
20
15
10
0
6.5
7
7.5
8
GAIN (dB)
8.5
9
25
20
15
10
5540 G19
0
45
90°C
25°C
–45°C
240
90°C
25°C
–45°C
40
35
30
25
20
15
10
5
5
180
200
220
IF FREQUENCY (MHz)
900MHz SSB Noise
Figure Distribution
DISTRIBUTION (%)
40
160
5540 G18
900MHz IIP3 Distribution
DISTRIBUTION (%)
45
5
140
1300
85°C
25°C
–40°C
5540 G17
5540 G16
DISTRIBUTION (%)
2LO–2RF
RF = 995MHz
–65
LO Switch Isolation
vs LO Frequency
PLO = –3dBm
PLO = 0dBm
PLO = +3dBm
PLO = +6dBm
20
–60
5540 G14
SSB Noise Figure
vs RF Blocker Level
22
RF = 900MHz
PRF = –10dBM
LO = 1090MHz
–70
5540 G13
24
2 × 2 and 3 × 3 Spur Suppression
vs LO Power
RELATIVE SPUR LEVEL (dBc)
20
OUTPUT POWER (dBm)
OUTPUT POWER (dBm/TONE)
2-Tone IF Output Power, IM3 and
IM5 vs RF Input Power
5
24 24.5 25 25.5 26 26.5 27 27.5 28
IIP3 (dBm)
5540 G20
0
8
8.5
9
9.5 10 10.5 11 11.5 12
NOISE FIGURE (dB)
5540 G21
5540f
LTC5540
Typical AC Performance Characteristics
Low-Side LO
VCC = 3.3V, VCCIF = 3.3V, SHDN = Low, TA = 25°C, PLO = 0dBm, PRF = –3dBm (–3dBm/tone for two-tone IIP3 tests, ∆f = 2MHz),
IF = 190MHz, unless otherwise noted. Test circuit shown in Figure 1.
900MHz SSB Noise Figure
vs RF Blocker Level
28
22
26
20
24
18
IIP3
14
18
18
12
16
10
14
85°C
25°C
–40°C
12
10
8
NF
6
800
14
12
4
10
2
900
0
1300
1000
1100
1200
RF FREQUENCY (MHz)
26
16
6
GC
8
SSB NF (dB)
20
SSB NF (dB)
20
28
PLO = –3dBm
PLO = 0dBm
PLO = +3dBm
PLO = +6dBm
22
16
22
GC (dB), IIP3 (dBm)
24
900MHz Conversion Gain, IIP3
and RF Input P1dB vs Temperature
GC (dB), IIP3 (dBm), P1dB (dBm)
Conversion Gain, IIP3 and NF
vs RF Frequency
–15
–10
–5
0
5
RF BLOCKER POWER (dBm)
5540 G22
18
16
14
P1dB
12
10
GC
8
6
–45
10
–25
–5 15
35 55
TEMPERATURE (°C)
75
95
5540 G24
1300MHz Conversion Gain, IIP3
and NF vs LO Power
1100MHz Conversion Gain, IIP3
and NF vs LO Power
28
20
26
18
24
18
24
18
22
16
22
16
22
16
20
14
20
14
20
14
18
12
18
12
18
12
16
10
16
10
16
10
85°C
25°C
–40°C
12
10
NF
8
6
GC
8
6
–6
–4
–2
0
2
4
LO INPUT POWER (dBm)
6
14
85°C
25°C
–40°C
12
4
10
2
8
0
6
–6
GC
–4
20
10
10 IFOUT
RF = 900MHz
0
OUTPUT POWER (dBm)
IFOUT
–20
RF1 = 899MHz
RF2 = 901MHz
–40 LO = 710MHz
–30
–50
–60
–80
–12
IM3
85°C
25°C
–40°C
12
4
10
2
8
0
6
–6
GC
6
4
–4
–2
0
2
4
LO INPUT POWER (dBm)
–30 LO = 710MHz
3RF–3LO
RF = 733.33MHz
–40
–50
6
0
5540 G27
–10
–20
8
NF
2
2 × 2 and 3 × 3 Spur Suppression
vs LO Power
–50
2RF–2LO
RF = 805MHz
–60
–55
2RF–2LO
RF = 805MHz
RF = 900MHz
PRF = –10dBM
LO = 710MHz
–60
–65
3RF–3LO
RF = 773.33MHz
–70
–75
–70
IM5
–9
–6
–3
0
3
RF INPUT POWER (dBm/TONE)
6
14
Single-Tone IF Output Power, 2 × 2
and 3 × 3 Spurs vs RF Input Power
20
–70
6
20
IIP3
5540 G26
2-Tone IF Output Power, IM3 and
IM5 vs RF Input Power
–10
8
–2
0
2
4
LO INPUT POWER (dBm)
5540 G25
0
NF
22
SSB NF (dB)
14
IIP3
RELATIVE SPUR LEVEL (dBc)
IIP3
GC (dB), IIP3 (dBm)
22
26
GC (dB), IIP3 (dBm)
28
20
SSB NF (dB)
22
26
SSB NF (dB)
28
24
GC (dB), IIP3 (dBm)
20
5540 G23
900MHz Conversion Gain, IIP3
and NF vs LO Power
OUTPUT POWER (dBm/TONE)
VCCIF = 5.0V
VCCIF = 3.3V
22
RF = 900MHz
BLOCKER = 1000MHz
8
–20
IIP3
24
6
5540 G28
–80
–12
–9
–6
–3
0
3
RF INPUT POWER (dBm)
6
5540 G29
–80
–6
–3
0
3
LO INPUT POWER (dBm)
6
5540 G30
5540f
LTC5540
Pin Functions
NC (Pin 1): This pin is not connected internally. It can be
left floating, connected to ground or to VCC .
LOBIAS (Pin 7): This Pin Allows Adjustment of the LO
Buffer Current. Typical DC voltage is 2.2V.
RF (Pin 2): Single-Ended Input for the RF Signal. This pin
is internally connected to the primary side of the RF input
transformer, which has low DC resistance to ground. A series
DC-blocking capacitor should be used to avoid damage
to the integrated transformer. The RF input is impedance
matched, as long as the selected LO input is driven with a
0dBm ±6dB source between 0.7GHz and 1.2GHz.
LOSEL (Pin 9): LO1/LO2 Select Pin. When the input voltage
is less than 0.3V, the LO1 port is selected. When the input
voltage is greater than 3V, the LO2 port is selected. Typical
input current is 11μA for LOSEL = 3.3V. This pin must not
be allowed to float.
CT (Pin 3): RF Transformer Secondary Center-Tap. This
pin may require a bypass capacitor to ground. See the
Applications Information section. This pin has an internally
generated bias voltage of 1.2V. It must be DC-isolated
from ground and VCC.
GND (Pins 4, 10, 12, 13, 17, Exposed Pad Pin 21):
Ground. These pins must be soldered to the RF ground
plane on the circuit board. The exposed pad metal of the
package provides both electrical contact to ground and
good thermal contact to the printed circuit board.
SHDN (Pin 5): Shutdown Pin. When the input voltage is
less than 0.3V, the internal circuits supplied through pins
6, 8, 14, 18 and 19 are enabled. When the input voltage
is greater than 3V, all circuits are disabled. Typical input
current is less than 10μA. This pin must not be allowed
to float.
VCC2 (Pin 6) and VCC1 (Pin 8): Power Supply Pins for
the LO Buffer and Bias Circuits. These pins are internally
connected and must be externally connected to a regulated
3.3V supply, with bypass capacitors located close to the
pin. Typical current consumption is 97mA.
LO1 (Pin 11) and LO2 (Pin 15): Single-Ended Inputs for
the Local Oscillators. These pins are internally biased
at 0V and require external DC blocking capacitors. Both
inputs are internally matched to 50Ω, even when the chip
is disabled (SHDN = high).
VCC3 (Pin 14): Power Supply Pin for the LO Switch. This
pin must be connected to a regulated 3.3V supply and
bypassed to ground with a capacitor near the pin. Typical
DC current consumption is less than 100μA.
IFGND (Pin 16): DC Ground Return for the IF Amplifier.
This pin must be connected to ground to complete the IF
amplifier’s DC current path. Typical DC current is 96mA.
IF – (Pin 18) and IF + (Pin 19): Open-Collector Differential
Outputs for the IF Amplifier. These pins must be connected
to a DC supply through impedance matching inductors, or
a transformer center-tap. Typical DC current consumption
is 48mA into each pin.
IFBIAS (Pin 20): This Pin Allows Adjustment of the IF Amp
Current. Typical DC voltage is 2.1V.
5540f
LTC5540
Block Diagram
20
19 18
21
16
IFBIAS
IF –
IFGND
EXPOSED
IF+
PAD
IF
AMP
2
3
5
LO2
15
VCC3
14
RF
LO
AMP
LOSEL
PASSIVE
MIXER
CT
SHDN
9
LO1
11
BIAS
VCC2
VCC1
6
8
7
LOBIAS
GND PINS ARE
NOT SHOWN
5540 BD
Test Circuit
IFOUT
190MHz
50Ω
4:1
T1
L1
VCCIF
3.1V TO 5.3V
96mA
C9
L1, L2 vs IF
Frequencies
C10
IF (MHz)
L1, L2 (nH)
L2
140
270
190
150
240
100
380
33
450
22
C8
L3
R2
20
19
18
IFBIAS IF+
IF –
17
16
GND
IFGND
1 NC
RFIN
50Ω
C4
LO2IN
50Ω
LO2 15
C1
2 RF
VCC3 14
C2
LTC5540
3 CT
C7
GND 13
4 GND
GND 12
C3
SHDN
(0V/3.3V)
5 SHDN
VCC2
LOBIAS
7
6
VCC
3.1V TO 3.5V
97mA
VCC1
LOSEL
9
8
LO1IN
50Ω
LO1 11
GND
10
REF DES
VALUE
SIZE
COMMENTS
C3, C4
100pF
0402
AVX
C6, C7, C8
22pF
0402
AVX
C5, C9
1µF
0603
AVX
C10
1000pF
0402
AVX
L1, L2
150nH
0603 Coilcraft 0603CS
L3
30nH
0603 Coilcraft 0603CS
R2
2.05k
0402
T1
(Alternate)
TC4-1W-7ALN+
(WBC4-6TLB)
Mini-Circuits
(Coilcraft)
HIGH-SIDE LO
C5
0.015”
0.062”
0.015”
5541 TC
C6
LOSEL
(0V/3.3V)
RF
GND
DC1431A
BOARD
BIAS STACK-UP
GND (NELCO N4000-13)
C1
5.6pF
0402
AVX
C2
1.5pF
0402
AVX
100pF
0402
AVX
LOW-SIDE LO
C1, C2
Figure 1. Standard Downmixer Test Circuit Schematic (190MHz IF)
5540f
LTC5540
Applications Information
Introduction
The LTC5540 consists of a high linearity passive doublebalanced mixer core, IF buffer amplifier, high speed singlepole double-throw (SPDT) LO switch, LO buffer amplifier
and bias/enable circuits. See Pin Functions section for a
description of each pin function. The RF and LO inputs
are single-ended. The IF output is differential. Low-side or
high-side LO injection can be used. The evaluation circuit,
shown in Figure 1, utilizes bandpass IF output matching and
an IF transformer to realize a 50Ω single-ended IF output.
The evaluation board layout is shown in Figure 2.
2mm of pin 3 for proper high-frequency decoupling. The
nominal DC voltage on the CT pin is 1.2V.
For the RF input to be properly matched, the selected
LO input must be driven. The values of C1 and C2 can
be chosen to optimize the performance for high-side
or low-side LO (see the table in Figure 1). For high-side
applications, a broadband input match is realized with
C1 = 5.6pF. The measured input return loss is shown in
Figure 4 for LO frequencies of 700MHz, 1090MHz and
1200MHz. As shown in Figure 4, the RF input impedance
is dependent on LO frequency, although a single value of
C1 is adequate to cover a wide RF range.
TO MIXER
RFIN
C1
2
3
RF
CT
C2
LTC5540
5540 F03
5540 F02
Figure 3. RF Input Schematic
Figure 2. Evaluation Board Layout
0
RF Input
The secondary winding of the RF transformer is internally
connected to the passive mixer. The center-tap of the
transformer secondary is connected to pin 3 (CT) to allow
the connection of bypass capacitor, C2. The value of C2
is LO frequency-dependent. C2 should be located within
–5
RETURN LOSS (dB)
The mixer’s RF input, shown in Figure 3, is connected to
the primary winding of an integrated transformer. A 50Ω
match is realized when a series capacitor, C1, is connected
to the RF input. C1 is also needed for DC blocking if the
RF source has DC voltage present, since the primary side
of the RF transformer is DC-grounded internally. The DC
resistance of the primary is approximately 5Ω.
LO = 700MHz
LO = 1090MHz
LO = 1200MHz
–10
–15
–20
–25
600
C1 = 5.6pF
700
800
900 1000
FREQUENCY (MHz)
1200
1100
5541 F04
Figure 4. RF Input Return Loss
5540f
10
LTC5540
Applications Information
The RF input impedance and input reflection coefficient,
versus RF frequency, is listed in Table 1. The reference
plane for this data is pin 2 of the IC, with no external
matching, and the LO is driven at 1090MHz.
Table 1. RF Input Impedance and S11
(at Pin 2, No External Matching, LO Input Driven at 1090MHz)
S11
The LO switch is designed for high isolation and fast
(36dBm OIP3 at 300MHz, Differential I/O
Fixed Gain of 8dB, 14dB, 20dB and 26dB; >40dBm OIP3 at 140MHz, Differential I/O
40.25dBm OIP3 to 300MHz, Programmable Fast Recovery Output Clamping
35dBm OIP3 at 240MHz, Continuous Gain Range –14dB to 17dB
48dBm OIP3 at 200MHz, 2dB to 18dB Gain Range, 0.125dB Gain Steps
Integrated Baluns, 28dBm IIP3, 13dBm P1dB, 0.03dB I/Q Amplitude Match,
0.4° Phase Match
27dBm OIP3 at 900MHz, 24.2dBm at 1.95GHz, Integrated RF Transformer
27.3dBm OIP3 at 2.14GHz, NF = 9.9dB, 3.3V Supply, Single-Ended LO and RF Ports
27.7dBm OIP3 at 140MHz, 22.9dBm at 900MHz, –161.2dBm/Hz Noise Floor
LT5581
ADCs
LTC2208
LTC2262-14
LTC2242-12
6GHz Low Power RMS Detector
40dB Dynamic Range, ±1dB Accuracy Over Temperature, 1.5mA Supply Current
16-Bit, 130Msps ADC
14-Bit, 150Msps ADC Ultralow Power
12-Bit, 250Msps ADC
78dBFS Noise Floor, >83dB SFDR at 250MHz
72.8dB SNR, 88dB SFDR, 149mW Power Consumption
65.4dB SNR, 78dB SFDR, 740mW Power Consumption
±1dB Output Variation over Temperature, 38ns Response Time, Log Linear
Response
Low Frequency to 1GHz, 83dB Log Linear Dynamic Range
±0.5dB Accuracy Over Temperature and >50dB Dynamic Range, 500ns Rise Time
5540f
16 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
LT 0410 • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 2010
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