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FEATURES

LT5575 800MHz to 2.7GHz High Linearity Direct Conversion Quadrature Demodulator DESCRIPTION
The LT(R)5575 is an 800MHz to 2.7GHz direct conversion quadrature demodulator optimized for high linearity receiver applications. It is suitable for communications receivers where an RF signal is directly converted into I and Q baseband signals with bandwidth up to 490MHz. The LT5575 incorporates balanced I and Q mixers, LO buffer amplifiers and a precision, high frequency quadrature phase shifter. The integrated on-chip broadband transformers provide 50 single-ended interfaces at the RF and LO inputs. Only a few external capacitors are needed for its application in an RF receiver system. The high linearity of the LT5575 provides excellent spurfree dynamic range for the receiver. This direct conversion demodulator can eliminate the need for intermediate frequency (IF) signal processing, as well as the corresponding requirements for image filtering and IF filtering. Channel filtering can be performed directly at the outputs of the I and Q channels. These outputs can interface directly to channel-select filters (LPFs) or to baseband amplifiers.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Operation over a wider frequency range is possible with reduced performance. Consult the factory.
Input Frequency Range: 0.8GHz to 2.7GHz* 50 Single-Ended RF and LO Ports High IIP3: 28dBm at 900MHz, 22.6dBm at 1.9GHz High IIP2: 54.1dBm at 900MHz, 60dBm at 1.9GHz Input P1dB: 13.2dBm at 900MHz I/Q Gain Mismatch: 0.04dB Typical I/Q Phase Mismatch: 0.4 Typical Low Output DC Offsets Noise Figure: 12.8dB at 900MHz, 12.7dB at 1.9GHz Conversion Gain: 3dB at 900MHz, 4.2dB at 1.9GHz Very Few External Components Shutdown Mode 16-Lead QFN 4mm x 4mm Package with Exposed Pad
APPLICATIONS

Cellular/PCS/UMTS Infrastructure RFID Reader High Linearity Direct Conversion I/Q Receiver
TYPICAL APPLICATION
High Signal-Level I/Q Demodulator for Wireless Infrastructure
+5V BPF LNA BPF RF INPUT VCC RF LT5575 VGA 0 IOUT- A/D
Conversion Gain, NF, IIP3 and IIP2 vs LO Input Power at 1900MHz
35 IIP2 GAIN (dB), NF (dB), IIP3 (dBm) 70 60 IIP3 50 IIP2 (dBm) 40 DSB NF -40C 25C 85C 30 20 10 0
IOUT+
LPF
30 25 20 15 10 5 0 -15
LO INPUT
LO 0/90 90
QOUT+ QOUT-
LPF VGA A/D
CONV GAIN
ENABLE
EN
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-5 -10 0 LO INPUT POWER (dBm)
5
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LT5575 ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW QOUT+ QOUT- 12 VCC 17 11 GND 10 LO 9 5 EN 6 VCC 7 VCC 8 VCC GND IOUT+ GND 1 RF 2 GND 3 GND 4 IOUT-
Power Supply Voltage ..............................................5.5V Enable Voltage ................................ -0.3V to VCC + 0.3V LO Input Power ....................................................10dBm RF Input Power ....................................................20dBm RF Input DC Voltage ...............................................0.1V LO Input DC Voltage ..............................................0.1V Operating Ambient Temperature ..............-40C to 85C Storage Temperature Range...................-65C to 125C Maximum Junction Temperature .......................... 125C CAUTION: This part is sensitive to electrostatic discharge (ESD). It is very important that proper ESD precautions be observed when handling the LT5575.
16 15 14 13
UF PACKAGE 16-LEAD (4mm x 4mm) PLASTIC QFN TJMAX = 125C, JA = 37C/W EXPOSED PAD (PIN #17) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH LT5575EUF#PBF TAPE AND REEL LT5575EUF#TRPBF PART MARKING 5575 PACKAGE DESCRIPTION 16-Lead (4mm x 4mm) QFN TEMPERATURE RANGE -40C to 85C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on nonstandard 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/
DC ELECTRICAL CHARACTERISTICS
PARAMETER Supply Voltage Supply Current Shutdown Current Turn On Time Turn Off Time EN = High (On) EN = Low (Off) EN Input Current Output DC Offset Voltage ( | IOUT+ - IOUT- |, | QOUT+ - QOUT- | ) Output DC Offset Variation vs Temperature VENABLE = 5V EN = Low CONDITIONS
VCC = +5V, TA = 25C, unless otherwise noted. (Note 3)
MIN 4.5 132 <1 120 750 2 1 120 <9 38 TYP MAX 5.25 155 100 UNITS V mA A ns ns V V A mV V/C
fLO = 1900MHz, PLO = 0dBm -40C to 85C
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LT5575 AC ELECTRICAL CHARACTERISTICS
PARAMETER RF Input Frequency Range LO Input Frequency Range Baseband Frequency Range Baseband I/Q Output Impedance RF Input Return Loss LO Input Return Loss LO Input Power Single-Ended ZO = 50, 1.5GHz to 2.7GHz, Internally Matched ZO = 50, 1.5GHz to 2.7GHz, Internally Matched CONDITIONS No External Matching (High Band) With External Matching (Low Band, Mid Band) No External Matching (High Band) With External Matching (Low Band, Mid Band)
Test circuit shown in Figure 1. (Notes 2, 3)
MIN TYP 1.5 to 2.7 0.8 to 1.5 1.5 to 2.7 0.8 to 1.5 DC to 490 65// 5pF >10 >10 -13 to 5 dB dB dBm MAX UNITS GHz GHz GHz GHz MHz
AC ELECTRICAL CHARACTERISTICS
PARAMETER Conversion Gain CONDITIONS
VCC = +5V, EN = High, TA = 25C, PRF = -10dBm (-10dBm/tone for 2-tone IIP2 and IIP3 tests), Baseband Frequency = 1MHz (0.9MHz and 1.1MHz for 2-tone tests), PLO = 0dBm, unless otherwise noted. (Notes 2, 3, 6)
MIN TYP 3 4.2 3.5 2 12.8 12.7 13.6 15.7 28 22.6 22.7 23.3 54.1 60 56 52.3 13.2 11.2 11 12.3 0.03 0.01 0.04 0.04 0.5 0.4 0.6 0.2 -60.8 -64.6 -60.2 -51.2 MAX UNITS dB dB dB dB dB dB dB dB dBm dBm dBm dBm dBm dBm dBm dBm dBm dBm dBm dBm dB dB dB dB dBm dBm dBm dBm
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Voltage Gain, RLOAD = 1k RF = 900MHz (Note 5) RF = 1900MHz RF = 2100MHz RF = 2500MHz RF = 900MHz (Note 5) RF = 1900MHz RF = 2100MHz RF = 2500MHz RF = 900MHz (Note 5) RF = 1900MHz RF = 2100MHz RF = 2500MHz RF = 900MHz (Note 5) RF = 1900MHz RF = 2100MHz RF = 2500MHz RF = 900MHz (Note 5) RF = 1900MHz RF = 2100MHz RF = 2500MHz RF = 900MHz (Note 5) RF = 1900MHz RF = 2100MHz RF = 2500MHz RF = 900MHz (Note 5) RF = 1900MHz RF = 2100MHz RF = 2500MHz RF = 900MHz (Note 5) RF = 1900MHz RF = 2100MHz RF = 2500MHz
Noise Figure (Double-Side Band, Note 4)
Input 3rd-Order Intercept
Input 2nd-Order Intercept
Input 1dB Compression
I/Q Gain Mismatch
I/Q Phase Mismatch
LO to RF Leakage
3
LT5575 AC ELECTRICAL CHARACTERISTICS
PARAMETER RF to LO Isolation CONDITIONS RF = 900MHz (Note 5) RF = 1900MHz RF = 2100MHz RF = 2500MHz
VCC = +5V, EN = High, TA = 25C, PRF = -10dBm (-10dBm/tone for 2-tone IIP2 and IIP3 tests), Baseband Frequency = 1MHz (0.9MHz and 1.1MHz for 2-tone tests), PLO = 0dBm, unless otherwise noted. (Notes 2, 3, 6)
MIN TYP 59.7 57.1 59.5 53.1 MAX UNITS dBc dBc dBc dBc
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: Tests are performed as shown in the configuration of Figure 1. Note 3: Specifications over the -40C to 85C temperature range are assured by design, characterization and correlation with statistical process control. Note 4: DSB Noise Figure is measured with a small-signal noise source at the baseband frequency of 15MHz without any filtering on the RF input and no other RF signal applied.
Note 5: 900MHz performance is measured with external RF and LO matching. The optional output capacitors C1-C4 (10pF) are also used for best IIP2 performance. Note 6: For these measurements, the complementary outputs (e.g., IOUT +, IOUT - ) were combined using a 180 phase shift combiner. Note 7: Large-signal noise figure is measured at an output frequency of 198.7MHz with RF input signal at fLO -1MHz. Both RF and LO input signals are appropriately bandpass filtered, as well as baseband output.
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LT5575
VCC = 5V, EN = High, TA = 25C, PRF = -10dBm (-10dBm/tone for 2-tone IIP2 and IIP3 tests), fBB = 1MHz (0.9MHz and 1.1MHz for 2-tone tests), PLO = 0dBm, unless otherwise noted. Test Circuit Shown in Figure 1 (Note 6). Conversion Gain, NF and IIP3 vs Frequency
35 GAIN (dB), NF (dB), IIP3 (dBm) 30 25 LOW MID 20 BAND BAND 15 10 5 0 800 CONV GAIN DSB NF IIP3 60 IIP2 (dBm) ICC (mA) HIGH BAND 55 50 45 40 800 -40C 25C 85C 1100 1400 1700 2000 2300 2600 RF INPUT FREQUENCY (MHz)
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TYPICAL AC PERFORMANCE CHARACTERISTICS
IIP2 vs Frequency
70 65 160 150 140
Supply Current vs Supply Voltage
-40C 25C 85C
85C
25C 130 120 - 40C 110 100 4.50
1100 1400 1700 2000 2300 2600 RF INPUT FREQUENCY (MHz)
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4.75 5.00 5.25 SUPPLY VOLTAGE (V)
5.50
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Conversion Gain vs RF Input Power
5 1900MHz 4 CONVERSION GAIN (dB) GAIN MISMATCH (dB) 900MHz 3 2500MHz 2 1 0 -1 -15 0.2 0.1 0.0 -0.1 -0.2 0.3
I/Q Gain Mismatch vs RF Input Frequency
fBB = 1MHz -40C 25C 85C PHASE MISMATCH (DEG) 3 2 1 0 1 2
I/Q Phase Mismatch vs RF Input Frequency
fBB = 1MHz -40C 25C 85C
-10
10 -5 0 5 RF INPUT POWER (dBm)
15
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-0.3 800
1100 1400 1700 2000 2300 2600 RF FREQUENCY (MHz)
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3 800
1100 1400 1700 2000 2300 2600 RF FREQUENCY (MHz)
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RF-LO Isolation vs RF Input Power
70 65 RF-LO ISOLATION (dBc) LO-RF LEAKAGE (dBm) 60 55 50 45 40 -16 900MHz 1900MHz 2500MHz - 40 - 45 -50 -55 - 60 -65 -70 -75 -12 -8 -4 0 RF INPUT POWER (dBm) 4 8
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LO-RF Leakage vs LO Input Power
6 5 CONV. GAIN (dB) 4 3 2 1 0
Conversion Gain vs Baseband Frequency
fLO = 1901MHz - 40C 25C 85C
2500MHz
900MHz
1900MHz
- 80 -15
-5 -10 0 LO INPUT POWER (dBm)
5
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0.1
1.0 10 100 BASEBAND FREQUENCY (MHz)
1000
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LT5575 TYPICAL AC PERFORMANCE CHARACTERISTICS VCC = 5V, EN = High, TA = 25C, PRF = -10dBm
(-10dBm/tone for 2-tone IIP2 and IIP3 tests), fBB = 1MHz (0.9MHz and 1.1MHz for 2-tone tests), PLO = 0dBm, unless otherwise noted. Test Circuit Shown in Figure 1 (Note 6). Conversion Gain, IIP3, NF vs LO Input Power at 900MHz
35 GAIN (dB), NF (dB), IIP3 (dBm) 30 25 20 15 10 5 0 -15 CONV GAIN DSB NF fLO = 901MHz OUTPUT POWER (dBm), IM3 (dBm) IIP3 10 -10 -30 -50 IM3 PRODUCT -70 -90 -40C 25C 85C -12 -8 -4 0 RF INPUT POWER (dBm) 4 8
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Output Power and IM3 vs RF Input Power at 900MHz
fLO = 901MHz OUTPUT POWER 70 65 60 IIP2 (dBm) 55 50 45 40 35
IIP2 vs LO Input Power at 900MHz
fLO = 901MHz -40C 25C 85C
-40C 25C 85C
-5 -10 0 LO INPUT POWER (dBm)
5
5575 G10
-110 -16
30 -15
-5 -10 0 LO INPUT POWER (dBm)
5
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Conversion Gain, IIP3, NF vs LO Input Power at 1900MHz
30 25 20 15 10 5 0 -15 CONV. GAIN DSB NF fLO = 1901MHz IIP3 OUTPUT POWER (dBm), IM3 (dBm) -40C 25C 85C 10 -10 -30 -50 -70 -90
Output Power and IM3 vs RF Input Power at 1900MHz
70 fLO = 1901MHz OUTPUT POWER 65 60 IM3 PRODUCT IIP2 (dBm) 55 50 -40C 25C 85C -12 -8 -4 0 RF INPUT POWER (dBm) 4 8
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IIP2 vs LO Input Power at 1900MHz
fLO = 1901MHz
GAIN (dB), NF (dB), IIP3 (dBm)
45 40 -15
-40C 25C 85C -10 -5 0 LO INPUT POWER (dBm) 5
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-10 -5 0 LO INPUT POWER (dBm)
5
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-110 -16
Conversion. Gain, IIP3, NF vs LO Input Power at 2500MHz
30 25 20 15 10 5 0 -15 -40C 25C 85C CONV. GAIN fLO = 2501MHz OUTPUT POWER (dBm), IM3 (dBm) IIP3 10 -10 -30
Output Power and IM3 vs RF Input Power at 2500MHz
fLO = 2501MHz OUTPUT POWER 60 IM3 PRODUCT -50 -70 -90 -40C 25C 85C -12 -8 -4 0 RF INPUT POWER (dBm) 4 8
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IIP2 vs LO Input Power at 2500MHz
70 65 fLO = 2501MHz -40C 25C 85C
GAIN (dB), NF (dB), IIP3 (dBm)
IIP2 (dBm)
55 50 45 40 35 30 -15 -5 -10 0 LO INPUT POWER (dBm) 5
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DSB NF
-10 -5 0 LO INPUT POWER (dBm)
5
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-110 -16
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LT5575 TYPICAL AC PERFORMANCE CHARACTERISTICS VCC = 5V, EN = High, TA = 25C, PRF = -10dBm
(-10dBm/tone for 2-tone IIP2 and IIP3 tests), fBB = 1MHz (0.9MHz and 1.1MHz for 2-tone tests), PLO = 0dBm, unless otherwise noted. Test Circuit Shown in Figure 1 (Notes 6, 7). I/Q Gain Mismatch vs LO Input Power
0.3 0.2 PHASE MISMATCH (DEG) GAIN MISMATCH (dB) 0.1 0.0 -0.1 -0.2 -0.3 -15 2500MHz 1900MHz 900MHz fBB = 1MHz 3 2 1 0 -1 -2 -3 -15
I/Q Phase Mismatch vs LO Input Power
30 fBB = 1MHz 900MHz 1900MHz 2500MHz 28 26 24 DSB NF (dB) 22 20 18 16 14 12
Large-Signal DSB NF vs RF Input Power
NOTE 7
900MHz 2500MHz 1900MHz
-10 -5 0 LO INPUT POWER (dBm)
5
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-10 -5 0 LO INPUT POWER (dBm)
5
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10 0 -30 -25 -20 -15 -10 -5 RF INPUT POWER (dBm)
5
10
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RF Port Return Loss
0 -5 RETURN LOSS (dB) -10 -15 -20 -25 LOW BAND; C10 = 4.7pF MID BAND; C10 = 2pF HIGH BAND; NO EXTERNAL COMPONENT RETURN LOSS (dB) 0
LO Port Return Loss
35 GAIN (dB), NF (dB), IIP3 (dBm) 30 25 20 15 10 5
Conversion Gain, IIP3, NF vs Supply Voltage
4.75V 5V 5.25V IIP3
-5
-10
-15 LOW BAND; C12 = 3.9pF MID BAND; C12 = 2.2pF HIGH BAND; NO EXTERNAL COMPONENT 1100 1400 1700 2000 2300 2600 FREQUENCY (MHz)
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DSB NF
-20
CONV. GAIN
-30 800 1100 1400 1700 2000 2300 2600 FREQUENCY (MHz)
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-25 800
0 800
1100 1400 1700 2000 2300 2600 RF FREQUENCY (MHz)
5575 G24
IIP2 vs Supply Voltage
70 65 60 IIP2 (dBm) 55 50 45 40 800 4.75V 5V 5.25V GAIN MISMATCH (dB) 0.3 0.2 0.1 0.0 -0.1 -0.2
I/Q Gain Mismatch vs Supply Voltage
4.75V 5V 5.25V PHASE MISMATCH (DEG) 3 2 1 0 -1 -2
I/Q Phase Mismatch vs Supply Voltage
4.75V 5V 5.25V
1100 1400 1700 2000 2300 2600 RF FREQUENCY (MHz) 5575 G25
-0.3 800
1100 1400 1700 2000 2300 2600 RF FREQUENCY (MHz) 5575 G26
-3 800
1100 1400 1700 2000 2300 2600 RF FREQUENCY (MHz) 5575 G27
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LT5575 TYPICAL AC PERFORMANCE CHARACTERISTICS VCC = 5V, EN = High, TA = 25C, PRF = -10dBm
(-10dBm/tone for 2-tone IIP2 and IIP3 tests), fBB = 1MHz (0.9MHz and 1.1MHz for 2-tone tests), PLO = 0dBm, unless otherwise noted. Test Circuit Shown in Figure 1 (Note 6). Conversion Gain Distribution at 1900MHz
50 45 40 DISTRIBUTION (%) DISTRIBUTION (%) 35 30 25 20 15 10 5 0 0 3.8 3.9 4 4.1 4.2 4.3 CONVERSION GAIN (dB) 4.4
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IIP3 Distribution at 1900MHz vs Temperature
30 25 20 15 10 5 - 40C 25C 85C DISTRIBUTION (%) 35 30 25 20 15 10 5 0
Noise Figure Distribution at 1900MHz
TA = 25C
TA = 25C
21.4 21.8 22.2 22.6 23 23.4 23.8 24.2 24.6 25 IIP3 (dBm)
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12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9 13 DSB NOISE FIGURE (dB)
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I/Q Amplitude Mismatch Distribution at 1900MHz vs Temperature
60 50 DISTRIBUTION (%) 40 30 20 10 0 -20 20 40 60 0 AMPLITUDE MISMATCH (mdB) 80
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I/Q Phase Mismatch Distribution at 1900MHz vs Temperature
25 -40C 25C 85C
-40C 25C 85C DISTRIBUTION (%)
20
15
10
5
0
-1.2 -0.8 -0.4 0 0.4 0.8 1.2 1.6 2.0 2.2 PHASE MISMATCH ()
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I-Output DC Offset Voltage Distribution vs Temperature
40 35 30 DISTRIBUTION (%) 25 20 15 10 5 0 2 4 6 8 10 12 14 DC OFFSET (mV) 16 18
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Q-Output DC Offset Voltage Distribution vs Temperature
40 35 30 DISTRIBUTION (%) 25 20 15 10 5 0 -10 -8 -6 -4 -2 0 2 DC OFFSET (mV) 4 6
5575 G34
-40C 25C 85C
- 40C 25C 85C
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LT5575 PIN FUNCTIONS
GND (Pins 1, 3, 4, 9, 11): Ground pin. RF (Pin 2): RF Input Pin. This is a single-ended 50 terminated input. No external matching network is required for the high frequency band. An external series capacitor (and/or shunt capacitor) may be required for impedance transformation to 50 in the low frequency band from 800MHz to 1.5GHz (see Figure 4). If the RF source is not DC blocked, a series blocking capacitor should be used. Otherwise, damage to the IC may result. VCC (Pins 6, 7, 8, 12): Power Supply Pins. These pins should be decoupled using 1000pF and 0.1F capacitors. EN (Pin 5): Enable Pin. When the input voltage is higher than 2.0V, the circuit is completely turned on. When the enable pin voltage is less than 1.0V, the circuit is turned off. Under no conditions should the voltage at the EN pin exceed VCC + 0.3V. Otherwise, damage to the IC may result. If the Enable function is not needed, then the EN pin should be tied to VCC. LO (Pin 10): Local Oscillator Input Pin. This is a singleended 50 terminated input. No external matching network is required in the high frequency band. An external shunt capacitor (and/or series capacitor) may be required for impedance transformation to 50 for the low frequency band from 800MHz to 1.5GHz (see Figure 6). If the LO source is not DC blocked, a series blocking capacitor must be used. Otherwise, damage to the IC may result. QOUT-, QOUT+ (Pins 13, 14): Differential Baseband Output Pins of the Q Channel. The internal DC bias voltage is VCC - 1.1V for each pin. I OUT-, I OUT+ (Pins 15, 16): Differential Baseband Output Pins of the I Channel. The internal DC bias voltage is VCC - 1.1V for each pin. Exposed Pad (Pin 17): Ground Return for the Entire IC. This pin must be soldered to the printed circuit board ground plane.
BLOCK DIAGRAM
VCC 6 VCC 7 VCC 8 VCC 12 RF AMP I-MIXER LPF 16 IOUT+ 15 IOUT- RF 2 LO BUFFERS GND 3 RF AMP LPF 0/90 10 LO 14 QOUT+ 13 QOUT- BIAS 1 4 GND 9 5 EN EXPOSED PAD 17
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11 GND
Q-MIXER
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LT5575 TEST CIRCUIT
J3 IOUT- C4 (OPT) J4 IOUT+ C3 (OPT) QOUT + QOUT - IOUT + IOUT - C1 (OPT) C2 (OPT) J6 QOUT- J5 QOUT+
J1 RF C10 (OPT)
GND RF GND GND VCC
VCC GND LO GND C5 1nF C12 (OPT) J2 LO
LT5575
VCC
VCC
EN
0.018" 0.062" 0.018"
r = 4.4
RF GND DC GND
EN R1 100K C7 1nF C8 0.1F
VCC C9 2.2F
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REF DES C5, C7 C8 C9 R1
VALUE 1000pF 0.1F 2.2F 100k
SIZE 0402 0402 3216 0402
PART NUMBER AVX 04025C102JAT AVX 0402ZD104KAT AVX TPSA225MO10R1800
FREQUENCY RANGE LOW BAND: 800 TO 1000MHz MID BAND: 1000 TO 1500MHz HIGH BAND: 1500 TO 2700MHz
RF MATCH C10 4.7pF 2pF -
LO MATCH C12 3.9pF 2pF -
BASEBAND C1-C4 10pF 2.2pF -
Figure 1. Evaluation Circuit Schematic
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Figure 2. Top Side of Evaluation Board
Figure 3. Bottom Side of Evaluation Board
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LT5575 APPLICATIONS INFORMATION
The LT5575 is a direct I/Q demodulator targeting high linearity receiver applications, such as RFID readers and wireless infrastructure. It consists of RF transconductance amplifiers, I/Q mixers, a quadrature LO phase shifter, and bias circuitry. The RF signal is applied to the inputs of the RF transconductance amplifiers and is then demodulated into I/Q baseband signals using quadrature LO signals which are internally generated from an external LO source by precision 90 phase-shifters. The demodulated I/Q signals are single-pole low-pass filtered on-chip with a -3dB bandwidth of 490MHz. The differential outputs of the I-channel and Q-channel are well matched in amplitude; their phases are 90 apart. Broadband transformers are integrated on-chip at both the RF and LO inputs to enable single-ended RF and LO interfaces. In the high frequency band (1.5GHz to 2.7GHz), both RF and LO ports are internally matched to 50. No external matching components are needed. For the lower frequency bands (800MHz to 1.5GHz), a simple network with series and/or shunt capacitors can be used as the impedance matching network. RF Input Port Figure 4 shows the demodulator's RF input which consists of an integrated transformer and high linearity transconductance amplifiers. The primary side of the transformer is connected to the RF input pin. The secondary side of the transformer is connected to the differential inputs of the transconductance amplifiers. Under no circumstances should an external DC voltage be applied to the RF input pin. DC current flowing into the primary side of the transformer may cause damage to the integrated transformer. A series blocking capacitor should be used to AC-couple the RF input port to the RF signal source. The RF input port is internally matched over a wide frequency range from 1.5GHz to 2.7GHz with input return loss typically better than 10dB. No external matching network is needed for this frequency range. When the part is operated at lower frequencies, however, the input return loss can be improved with the matching network shown in Figure 4. Shunt capacitor C10 and series capacitor C11 can be selected for optimum input impedance matching at the
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desired frequency as illustrated in Figure 5. For lower frequency band operation, the external matching component C11 can serve as a series DC blocking capacitor.
EXTERNAL MATCHING NETWORK FOR LOW BAND AND MID BAND C11 2 C10 3 TO Q-MIXER RF
RF INPUT
TO I-MIXER
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Figure 4. RF Input Interface
0 -5 -10 -15 -20 -25 -30 0.5 1.0 1.5 2.0 FREQUENCY (GHz) 2.5 3.0
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RF PORT RETURN LOSS (dB)
C11 = 5.6pF; C10 = 4.7pF C11 = 3.9pF; NO SHUNT CAP
NO EXTERNAL MATCHING
Figure 5. RF Input Return Loss with External Matching
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LT5575 APPLICATIONS INFORMATION
The RF input impedance and S11 parameters (without external matching components) are listed in Table 1.
Table 1. RF Input Impedance
FREQUENCY (GHz) 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 INPUT IMPEDANCE () 8.1 +j 21.3 10.5 +j 24.9 13.8 +j 28.8 18.6 +j 32.5 25.2 +j 35.5 33.6 +j 36.8 43.1 +j 34.6 51.4 +j 28.4 55.8 +j 19.3 55.4 +j 10.4 51.8 +j 3.9 46.9 +j 0.4 42.3 +j -0.8 38.4 +j -0.3 35.4 +j 1 33 +j 2.9 31.5 +j 4.9 30.4 +j 7 29.9 +j 9.1 29.7 +j 11.1 S11 MAG 0.760 0.715 0.660 0.595 0.521 0.441 0.355 0.270 0.188 0.110 0.042 0.032 0.084 0.131 0.172 0.207 0.235 0.258 0.274 0.287 ANGLE () 133.0 125.4 117.2 108.6 99.6 90.3 80.8 71.6 63 56.9 63 172.7 -173.9 -178.2 175.3 168.4 161.9 155.4 149.2 143.4
LO PORT RETURN LOSS (dB) -5 -10 -15 -20 -25 -30 0.5 1.0 1.5 2.0 FREQUENCY (GHz) 2.5 3.0
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The LO input port is internally matched over a wide frequency range from 1.5GHz to 2.7GHz with input return loss typically better than 10dB. No external matching network is needed for this frequency range. When the part is operated at a lower frequency, the input return loss can be improved with the matching network shown in Figure 6. Shunt capacitor C12 and series capacitor C13 can be selected for optimum input impedance matching at the desired frequency as illustrated in Figure 7. For lower frequency operation, external matching component C13 can serve as the series DC blocking capacitor.
EXTERNAL MATCHING NETWORK FOR LOW BAND AND MID BAND C13 C12
11 LO QUADRATURE GENERATOR AND BUFFER AMPLIFIERS 10 LO
LO INPUT
Figure 6. LO Input Interface
0 C13 = 5.6pF; C12 = 3.9pF
NO EXTERNAL MATCHING
LO Input Port The demodulator's LO input interface is shown in Figure 6. The input consists of an integrated transformer and a precision quadrature phase shifter which generates 0 and 90 phase-shifted LO signals for the LO buffer amplifiers driving the I/Q mixers. The primary side of the transformer is connected to the LO input pin. The secondary side of the transformer is connected to the differential inputs of the LO quadrature generator. Under no circumstances should an external DC voltage be applied to the input pin. DC current flowing into the primary side of the transformer may damage the transformer. A series blocking capacitor should be used to AC-couple the LO input port to the LO signal source.
C13 = 5.6pF; NO SHUNT CAP
Figure 7. LO Input Return Loss with External Matching
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LT5575 APPLICATIONS INFORMATION
The LO input impedance and S11 parameters (without external matching components) are listed in Table 2.
Table 2. LO Input Impedance
FREQUENCY (GHz) 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 INPUT IMPEDANCE () 9.6 +j 23.7 13 +j 27.1 17.9 +j 30 24.1 +j 31.7 31.2 +j 31.4 37.5 +j 28.9 41.9 +j 24.6 43.4 +j 20 42.9 +j 16.4 41.2 +j 14.1 39.5 +j 13.1 37.8 +j 13.1 36.6 +j 13.6 35.6 +j 14.6 35.1 +j 15.7 34.9 +j 17.1 35.1 +j 18.5 35.5 +j 19.9 36.3 +j 21.2 37.2 +j 22.5 S11 MAG 0.731 0.669 0.592 0.508 0.421 0.341 0.272 0.221 0.189 0.18 0.186 0.201 0.217 0.236 0.25 0.264 0.272 0.281 0.284 0.287 ANGLE () 127.9 120.4 113.2 106.1 99.8 95.1 93.4 96.2 103.5 113.1 120.3 124.5 125.6 125 123.1 120.1 116.6 113 109 105.1
I-Channel and Q-Channel Outputs Each of the I-channel and Q-channel outputs is internally connected to VCC through a 65 resistor. The output DC bias voltage is VCC - 1.1V. The outputs can be DC-coupled or AC-coupled to the external loads. Each single-ended output has an impedance of 65 in parallel with a 5pF internal capacitor, forming a low-pass filter with a -3dB corner frequency at 490MHz. The loading resistance on each output, RLOAD (single-ended), should be larger than 300 to assure full gain. The gain is reduced by 20 * log10(1 + 65/RLOAD) in dB when the output port is terminated by RLOAD. For instance, the gain is reduced by 7.23dB when each output pin is connected to a 50 load (or 100 differentially). The output should be taken differentially (or by using differential-to-singleended conversion) for best RF performance, including NF and IM2. The phase relationship between the I-channel output signal and the Q-channel output signal is fixed. When the LO input frequency is larger (or smaller) than the RF input frequency, the Q-channel outputs (QOUT+, QOUT- ) lead (or lag) the I-channel outputs (IOUT+, IOUT- ) by 90. When AC output coupling is used, the resulting highpass filter's -3dB roll-off frequency is defined by the RC constant of the blocking capacitor and RLOAD, assuming RLOAD >> 65.
VCC 5pF 65 65 5pF 5pF 65 65 5pF IOUT+ IOUT- QOUT+ QOUT- 16 15 14 13
5575 F08
Figure 8. I/Q Output Equivalent Circuit
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LT5575 APPLICATIONS INFORMATION
Care should be taken when the demodulator's outputs are DC-coupled to the external load to make sure that the I/Q mixers are biased properly. If the current drain from the outputs exceeds 6mA, there can be significant degradation of the linearity performance. Each output can sink no more than 16.8mA when the outputs are connected to an external load with a DC voltage higher than VCC - 1.1V. The I/Q output equivalent circuit is shown in Figure 8. In order to achieve best IIP2 performance, it is important to minimize high frequency coupling among the baseband outputs, RF port and LO port. For a multilayer PCB layout design, the metal lines of the baseband outputs should be placed on the backside of the PCB as shown in Figures 2 and 3. Typically, output shunt capacitors C1-C4 are not required for the application near 1900MHz. However, for other frequency bands, these capacitors can be optimized for best IIP2 performance. For example, when the operating frequency is 900MHz, the IIP2 can be improved to 54dBm or better when 10pF shunt capacitors are placed at each output.
VCC
Enable Interface A simplified schematic of the EN pin is shown in Figure 9. The enable voltage necessary to turn on the LT5575 is 2V. To disable or turn off the chip, this voltage should be below 1V. If the EN pin is not connected, the chip is disabled. However, it is not recommended that the pin be left floating for normal operation. It is important that the voltage applied to the EN pin should never exceed VCC by more than 0.3V. Otherwise, the supply current may be sourced through the upper ESD protection diode connected at the EN pin. Under no circumstances should voltage be applied to the EN pin before the supply voltage is applied to the VCC pin. If this occurs, damage to the IC may result.
LT5575
5
EN 60k 60k
5575 F09
Figure 9. Enable Pin Simplified Circuit
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LT5575 PACKAGE DESCRIPTION
UF Package 16-Lead Plastic QFN (4mm x 4mm) (Reference LTC DWG # 05-08-1692)
0.72 0.05
4.35 0.05 2.15 0.05 2.90 0.05 (4 SIDES)
PACKAGE OUTLINE 0.30 0.05 0.65 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS BOTTOM VIEW--EXPOSED PAD 4.00 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6) 2.15 0.10 (4-SIDES) 0.75 0.05 R = 0.115 TYP PIN 1 NOTCH R = 0.20 TYP OR 0.35 x 45 CHAMFER
15
16 0.55 0.20 1 2
(UF16) QFN 10-04
0.200 REF 0.00 - 0.05 NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGC) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE
0.30 0.05 0.65 BSC
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LT5575 RELATED PARTS
Ultralow Distortion, IF Amplifier/ADC Driver with Digitally Controlled Gain LT5515 1.5GHz to 2.5GHz Direct Conversion Quadrature Demodulator LT5516 0.8GHz to 1.5GHz Direct Conversion Quadrature Demodulator LT5517 40MHz to 900MHz Quadrature Demodulator LT5518 1.5GHz to 2.4GHz High Linearity Direct Quadrature Modulator LT5519 0.7GHz to 1.4GHz High Linearity Upconverting Mixer LT5520 1.3GHz to 2.3GHz High Linearity Upconverting Mixer LT5521 10MHz to 3700MHz High Linearity Upconverting Mixer LT5522 600MHz to 2.7GHz High Signal Level Downconverting Mixer LT5524 Low Power, Low Distortion ADC Driver with Digitally Programmable Gain LT5525 High Linearity, Low Power Downconverting Mixer LT5526 High Linearity, Low Power Downconverting Mixer LT5527 400MHz to 3.7GHz High Signal Level Downconverting Mixer LT5528 1.5GHz to 2.4GHz High Linearity Direct Quadrature Modulator LT5558 600MHz to 1100MHz High Linearity Direct Quadrature Modulator LT5560 Ultra-Low Power Active Mixer LT5568 700MHz to 1050MHz High Linearity Direct Quadrature Modulator LT5572 1.5GHz to 2.5GHz High Linearity Direct Quadrature Modulator RF Power Detectors LTC(R)5505 RF Power Detectors with >40dB Dynamic Range LTC5507 100kHz to 1000MHz RF Power Detector LTC5508 300MHz to 7GHz RF Power Detector LTC5509 300MHz to 3GHz RF Power Detector LTC5530 300MHz to 7GHz Precision RF Power Detector LTC5531 300MHz to 7GHz Precision RF Power Detector LTC5532 300MHz to 7GHz Precision RF Power Detector LT5534 50MHz to 3GHz Log RF Power Detector with 60dB Dynamic Range LTC5536 Precision 600MHz to 7GHz RF Power Detector with Fast Comparator Output LT5537 Wide Dynamic Range Log RF/IF Detector PART NUMBER Infrastructure LT5514 DESCRIPTION COMMENTS 850MHz Bandwidth, 47dBm OIP3 at 100MHz, 10.5dB to 33dB Gain Control Range 20dBm IIP3, Integrated LO Quadrature Generator 21.5dBm IIP3, Integrated LO Quadrature Generator 21dBm IIP3, Integrated LO Quadrature Generator 22.8dBm OIP3 at 2GHz, -158.2dBm/Hz Noise Floor, 50 Single-Ended RF and LO Ports, 4-Channel W-CDMA ACPR = -64dBc at 2.14GHz 17.1dBm IIP3 at 1GHz, Integrated RF Output Transformer with 50 Matching, Single-Ended LO and RF Ports Operation 15.9dBm IIP3 at 1.9GHz, Integrated RF Output Transformer with 50 Matching, Single-Ended LO and RF Ports Operation 24.2dBm IIP3 at 1.95GHz, NF = 12.5dB, 3.15V to 5.25V Supply, Single-Ended LO Port Operation 4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz, NF = 12.5dB, 50 Single-Ended RF and LO Ports 450MHz Bandwidth, 40dBm OIP3, 4.5dB to 27dB Gain Control Single-Ended 50 RF and LO Ports, 17.6dBm IIP3 at 1900MHz, ICC = 28mA 3V to 5.3V Supply, 16.5dBm IIP3, 100kHz to 2GHz RF, NF = 11dB, ICC = 28mA, -65dBm LO-RF Leakage IIP3 = 23.5dBm and NF = 12.5dBm at 1900MHz, 4.5V to 5.25V Supply, ICC = 78mA, Conversion Gain = 2dB 21.8dBm OIP3 at 2GHz, -159.3dBm/Hz Noise Floor, 50, 0.5VDC Baseband Interface, 4-Channel W-CDMA ACPR = -66dBc at 2.14GHz 22.4dBm OIP3 at 900MHz, -158dBm/Hz Noise Floor, 3k, 2.1VDC Baseband Interface, 3-Ch CDMA2000 ACPR = -70.4dBc at 900MHz 10mA Supply Current, 10dBm IIP3, 10dB NF, Usable as Up- or Down-Converter. 22.9dBm OIP3 at 850MHz, -160.3dBm/Hz Noise Floor, 50, 0.5VDC Baseband Interface, 3-Ch CDMA2000 ACPR = -71.4dBc at 850MHz 21.6dBm OIP3 at 2GHz, -158.6dBm/Hz Noise Floor, High-Ohmic 0.5VDC Baseband Interface, 4-Ch W-CDMA ACPR = -67.7dBc at 2.14GHz 300MHz to 3GHz, Temperature Compensated, 2.7V to 6V Supply 100kHz to 1GHz, Temperature Compensated, 2.7V to 6V Supply 44dB Dynamic Range, Temperature Compensated, SC70 Package 36dB Dynamic Range, Low Power Consumption, SC70 Package Precision VOUT Offset Control, Shutdown, Adjustable Gain Precision VOUT Offset Control, Shutdown, Adjustable Offset Precision VOUT Offset Control, Adjustable Gain and Offset 1dB Output Variation over Temperature, 38ns Response Time, Log Linear Response 25ns Response Time, Comparator Reference Input, Latch Enable Input, -26dBm to +12dBm Input Range Low Frequency to 1GHz, 83dB Log Linear Dynamic Range
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16 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 0107 * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2007

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