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LT5511 High Signal Level Upconverting Mixer
FEATURES
s s s s s s s s s s
DESCRIPTIO
Wide RF Output Frequency Range to 3000MHz Broadband RF and IF Operation +17dBm Typical Input IP3 (at 950MHz) +6dBm IF Input for 1dB RF Output Compression Integrated LO Buffer: -10dBm Drive Level Single-Ended or Differential LO Input Double-Balanced Mixer Enable Function Single 4.0V - 5.25V Supply Voltage Range 16-Pin TSSOP Exposed Pad Package
The LT(R)5511 mixer is designed to meet the high linearity requirements of cable TV infrastructure downstream transmitters and wireless infrastructure transmit systems. The IC includes a differential LO buffer amplifier driving a double-balanced mixer. The LO, RF and IF ports can be easily matched to a broad range of frequencies for different applications. The high performance capability of the LO buffer allows the use of a single-ended source, thus eliminating the need for an LO balun. The LT5511 mixer delivers +17dBm typical input 3rd order intercept point at 950MHz, and +15.5dBm IIP3 at 1900MHz, with IF input signal levels of - 5dBm. The input 1dB compression point is typically +6dBm.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s s s
CATV Downlink Infrastructure Wireless Infrastructure High Linearity Mixer Applications
TYPICAL APPLICATIO
ENABLE LT5511 EN
VCC 5V
VCCBIAS
VCCLO 950MHz TO DOWNMIXER
POUT, IM3 (dBm/TONE)
BIAS 44MHz MOD IF+ IF- RF + RF -
GND LO+ LO INPUT 994MHz -10dBm LO-
5511 F01a
Figure 1. High Signal Level Upmixer for CATV Downlink Infrastructure.
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RF Output Power and 3rd Order Intermodulation vs Input Power (Two Input Tones)
10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -20 PLO = -10dBm fRF1 = 950MHz fRF2 = 949MHz TA = 25C -15 -5 0 -10 IF INPUT POWER (dBm/TONE) 5
5511 F01b
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POUT
IM3
1
LT5511
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW LO- NC GND IF+ IF- GND VCCBIAS GND 1 2 3 4 5 6 7 8 16 LO
+
Supply Voltage ....................................................... 5.5V Enable Voltage ................................ -0.3V to VCC + 0.3V LO Input Power (Differential) .............................. 10dBm IF Input Power (Differential) ............................... 10dBm IF+, IF- DC Currents .............................................. 25mA Operating Temperature Range .................-40C to 85C Storage Temperature Range ..................-65C to 150C Lead Temperature (Soldering, 10sec)................... 300C
ORDER PART NUMBER LT5511EFE
15 VCCLO 14 GND 13 RF+ 12 RF - 11 GND 10 EN 9 NC
FE PART MARKING 5511EFE
FE PACKAGE 16-LEAD PLASTIC TSSOP
TJMAX = 150C, JA = 38C/W EXPOSED PAD IS GROUND (MUST BE SOLDERED TO PRINTED CIRCUIT BOARD)
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER VCC = 5VDC, EN = High, TA = 25C IF Input Frequency Range (Note 6) LO Input Frequency Range (Note 6) RF Output Frequency Range (Note 6) 1 to 300 30 to 2700 10 to 3000 MHz MHz MHz CONDITIONS MIN TYP MAX UNITS
950MHz Application: (Test Circuit Shown in Figure 2) VCC = 5VDC, EN = High, TA = 25C, IF Input = 50MHz at -5dBm, LO Input = 1GHz at -10dBm, RF Output Measured at 950MHz, unless otherwise noted. (Notes 2, 3) IF Input Return Loss LO Input Power LO Input Return Loss RF Output Return Loss Conversion Gain LO to RF Leakage Input 1dB Compression Input 3rd Order Intercept Input 2nd Order Intercept SSB Noise Figure Two-Tone, -5dBm/Tone, f = 1MHz Single-Tone, -5dBm With External Matching, ZO = 50 With External Matching, ZO = 50 With External Matching, ZO = 50 14 -15 to -5 14 17 0 -46 5.9 17 52 15 dB dBm dB dB dB dBm dBm dBm dBm dB
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LT5511
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS 1.9GHz Application: (Test Circuit Shown in Figure 3) VCC = 5VDC, EN = High, TA = 25C, IF Input = 50MHz at -5dBm, LO Input = 1.95GHz at -10dBm, RF Output Measured at 1900MHz, unless otherwise noted. (Notes 3, 4) IF Input Return Loss LO Input Power LO Input Return Loss RF Output Return Loss Conversion Gain LO to RF Leakage Input 1dB Compression Input 3rd Order Intercept Input 2nd Order Intercept SSB Noise Figure Power Supply Requirements: VCC = 5VDC, EN = High, TA = 25C, unless otherwise noted. Supply Voltage Supply Current Shutdown Current (Chip Disabled) Enable Mode Threshold Disable Mode Threshold Turn ON Time (Note 5) Turn OFF Time (Note 5) Enable Input Current EN = 5V EN = Low EN = High EN = Low 2 6 1 3 0.5 4.0 to 5.25 56 1 65 30 VDC mA A VDC VDC s s A Two-Tone, -5dBm/Tone, f = 1MHz Single-Tone, -5dBm With External Matching, ZO = 50 With External Matching, ZO = 50 With External Matching, ZO = 50 14 -15 to -5 11.5 11.5 -0.7 -47 5.2 15.5 51 14 dB dBm dB dB dB dBm dBm dBm dBm dB
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: External components on the final test circuit are optimized for operation at f RF = 950MHz, f LO = 1GHz and f IF = 50MHz (Figure 2). Note 3: Specifications over the - 40C to 85C temperature range are assured by design, characterization and correlation with statistical process controls.
Note 4: External components on the final test circuit are optimized for operation at f RF = 1900MHz, f LO = 1.95GHz and f IF = 50MHz (Figure 3). Note 5: Turn On and Turn Off times are based on rise and fall times of RF output envelope from full power to -40dBm with an IF input power of -5dBm. Note 6: Part can be used over a broader range of operating frequencies. Consult factory for applications assistance.
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(950MHz Application) VCC = 5VDC, EN = High , TA = 25C, IF Input = 50MHz at -5dBm, LO Input = 1GHz at -10dBm, RF Output Measured at 950MHz, unless otherwise noted. For 2-Tone Measurements: 2nd IF Input = 51MHz at -5dBm. (Test Circuit Shown in Figure 2). RF Output Power and 3rd Order Intermodulation vs IF Input Power (Two Input Tones)
10 0 -10 POUT, IM3 (dBm/TONE) -20 -30 -40 -50 -60 -70 -80 -15 -10 0 -5 IF INPUT POWER (dBm/TONE)
5511 G01
TYPICAL PERFOR A CE CHARACTERISTICS
TA = 25C TA = -40C TA = 85C IM3 TA = 25C
POUT, IM2 (dBm)
-30 -40 -50 -60 -70 IM2 TA = -40C TA = 25C TA = 85C
GAIN (dB)
TA = -40C
TA = 85C
Conversion Gain and IIP3 vs LO Power
8 IIP3 TA = 25C TA = 85C
GAIN (dB)
TA = -40C
IIP3 (dBm)
LO TO RF LEAKAGE (dBm)
6
IIP2 (dBm)
4
2
GAIN
TA = -40C TA = 25C TA = 85C 11
0
-2 -20
-15
-10 LO POWER (dBm)
-5
Conversion Gain and LO to RF Leakage vs Output Frequency
2 0 GAIN -2 TA = 25C TA = 85C -4 -6 LO LEAKAGE -8 IF = 50MHz, LO SWEPT FROM 400MHz TO 1300MHz AT -10dBm -10 300 500 700 900 1100 RF OUTPUT FREQUENCY (MHz) TA = 25C -55 -65 1300
5511 G07
TA = -40C
IIP3, IIP2 (dBm)
TA = 85C TA = -40C
-25 -35 -45
40 30 20 10
GAIN (dB)
TA = 25C IIP3 TA = 85C TA = 25C TA = -40C
NOISE FIGURE (dB)
4
UW
POUT 5
9 0
5511 G04
RF Output Power and 2nd Order Intermodulation vs IF Input Power (Single Input Tone)
10 0 -10 -20 POUT TA = 25C TA = -40C TA = 85C
Conversion Gain vs IF Input Power (Single Input Tone)
5 4 3 2 1 0 -1 -2 -3 -4 TA = 25C TA = 85C TA = -40C
-80 -15
-10 0 -5 IF INPUT POWER (dBm)
5511 G02
5
-5 -15
-10 0 -5 IF INPUT POWER (dBm)
5
5511 G03
LO to RF Leakage vs LO Power
19
IIP2 vs LO Power
60 TA = -40C 50 TA = 25C 40 TA = 85C
-5
17
-15
15
-25
30 20
13
-35 TA = 85C -45 TA = 25C -55 -20 -15 -10 LO POWER (dBm)
5511 G05
TA = -40C
10 0 -20
-5
0
-15
-10 -5 LO POWER (dBm)
0
5511 G06
-5 -15
60 50
IIP3 and IIP2 vs Output Frequency
IIP2 TA = 85C 18 TA = -40C 20
SSB Noise Figure vs Output Frequency
TA = 25C
LO TO RF LEAKAGE (dBm)
16
14
12 IF = 50MHz, LO SWEPT FROM 400MHz TO 1300MHz AT -10dBm 10 300 500 700 900 1100 RF OUTPUT FREQUENCY (MHz)
IF = 50MHz, LO SWEPT FROM 400MHz TO 1300MHz AT -10dBm 0 300 500 700 900 1100 RF OUTPUT FREQUENCY (MHz)
1300
5511 G08
1300
5511 G09
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LT5511
(950MHz Application) VCC = 5VDC, EN = High , TA = 25C, IF Input = 50MHz at -5dBm, LO Input = 1GHz at -10dBm, RF Output Measured at 950MHz, unless otherwise noted. For 2-Tone Measurements: 2nd IF Input = 51MHz at -5dBm. (Test Circuit Shown in Figure 2). LO and RF Port Return Loss vs Frequency
0
6
TYPICAL PERFOR A CE CHARACTERISTICS
Conversion Gain vs Supply Voltage
-10
RETURN LOSS (dB)
RF PORT
IIP3 (dBm)
GAIN (dB)
2 25
-20 LO PORT -30
-40
-50 300
500
900 700 1100 FREQUENCY(MHz)
(1.9GHz Application) VCC = 5VDC, EN = High , TA = 25C, IF Input = 50MHz at -5dBm, LO Input = 1.95GHz at -10dBm, RF Output Measured at 1900MHz, unless otherwise noted. For 2-Tone Measurements: 2nd IF Input = 51MHz at -5dBm. (Test Circuit Shown in Figure 3). RF Output Power and 3rd Order Intermodulation vs IF Input Power (Two Input Tones)
10 0 -10
POUT, IM3 (dBm/TONE)
TA = 25C
TA = -40C
TA = 85C
POUT, IM2 (dBm)
-20 -30 -40 -50 -60 -70 -80 -15 TA = 85C TA = 25C TA = -40C
-30 -40 -50 -60 -70 TA = -40C TA = 85C TA = 25C -10 0 -5 IF INPUT POWER (dBm)
5511 G14
GAIN (dB)
-10 0 -5 IF INPUT POWER (dBm/TONE)
5511 G13
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5511 G10
IIP3 and IIP2 vs Supply Voltage
35 IIP2 TA = 25C TA = -40C TA = 85C 50 60
4
30
TA = -40C TA = 25C TA = 85C
40
IIP2 (dBm)
0
20 IIP3 15 TA = 25C
TA = 85C TA = -40C
30
-2
20
1300
-4 4.0
4.2
4.4 4.6 4.8 5.0 5.2 SUPPLY VOLTAGE (V)
5.4 5.6
5511 G11
10 4.0
4.2
4.4 4.6 4.8 5.0 5.2 SUPPLY VOLTAGE (V)
10 5.4 5.6
5511 G12
RF Output Power and 2nd Order Intermodulation vs IF Input Power (Single Input Tone)
10 0 -10 -20 TA = 25C TA = -40C POUT
5 4 3
Conversion Gain vs IF Input Power (Single Input Tone)
POUT
IM3
TA = 85C
2 1 0 -1 -2 -3 -4 TA = 25C TA = 85C TA = -40C
IM2
5
-80 -15
5
-5 -15
-10 0 -5 IF INPUT POWER (dBm)
5
5511 G15
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(1.9GHz Application) VCC = 5VDC, EN = High , TA = 25 C, IF Input = 50MHz at -5dBm, LO Input = 1.95GHz at -10dBm. RF Output Measured at 1900MHz, unless otherwise noted. For 2-Tone Measurements: 2nd IF Input = 51MHz at -5dBm. (Test Circuit Shown in Figure 3). Conversion Gain and IIP3 vs LO Input Power
6 IIP3 17 TA = 85C LO TO RF LEAKAGE (dBm) TA = 25C TA = -40C GAIN TA = -40C 0 TA = 25C -2 TA = 85C 9 11 15 -5 -15 -25 TA = -40C -35 -45 TA = 25C -4 -25 -10 -15 -5 -20 LO INPUT POWER (dBm) 7 0
5511 G16
TYPICAL PERFOR A CE CHARACTERISTICS
LO to RF Leakage vs LO Input Power
5
4
IIP2 (dBm)
GAIN (dB)
2
Conversion Gain and LO to RF Leakage vs RF Output Frequency
2 GAIN TA = -40C TA = 25C TA = 85C -15
LO TO RF LEAKAGE (dBm)
0
GAIN (dB)
-2
IIP3, IIP2 (dBm)
40 30 20 10 0 1500
TA = -40C
NOISE FIGURE (dB)
-4
LO LEAKAGE TA = 85C
TA = 25C
-6 IF = 50MHz, LO SWEPT FROM 1600MHz TO 2350MHz
TA = -40C -45 -55 2300
5511 G19
-8 1500
1700 1900 2100 RF OUTPUT FREQUENCY (MHz)
LO and RF Port Return Loss vs Frequency
0 -5 LO PORT
RETURN LOSS (dB)
-10
GAIN (dB)
RF PORT -15 -20 -25 -30 1500
0
TA = 25C TA = 85C
IIP3 (dBm)
2100 1900 1700 FREQUENCY(MHz)
6
UW
5511 G22
IIP2 vs LO Input Power
60 TA = 25C 50 40 30 20 10 0 -25 TA = -40C TA = 85C
IIP3 (dBm)
13
TA = 85C
-55 -25
-10 -15 -5 -20 LO INPUT POWER (dBm)
0
5511 G17
-20 -15 -10 -5 LO INPUT POWER (dBm)
0
5511 G18
IIP3 and IIP2 vs Output Frequency
-5 60 50 IIP2 TA = 85C TA = 25C 18 20
SSB Noise Figure vs Output Frequency
TA = 25C
-25
16
IIP3 TA = 25C TA = 85C TA = -40C IF = 50MHz, LO SWEPT FROM 1600MHz TO 2350MHz 1700 1900 2100 RF OUTPUT FREQUENCY (MHz) 2300
5511 G20
-35
14
12 IF = 50MHz, LO SWEPT FROM 1600MHz TO 2350MHz 10 1500 1700 1900 2100 RF OUTPUT FREQUENCY (MHz)
2300
5511 G21
Conversion Gain vs Supply Voltage
4
30
IIP3 and IIP2 vs Supply Voltage
60 IIP2 TA = 25C TA = -40C 50 TA = 85C 20 IIP3 15 TA = 25C TA = -40C TA = 85C 30 40
2 TA = -40C
25
IIP2 (dBm)
-2
-4
10
20
2300
-6 4.0
4.2
4.4 4.6 4.8 5.0 5.2 SUPPLY VOLTAGE (V)
5.4 5.6
5511 G23
5 4.0
4.2
4.4 4.6 4.8 5.0 5.2 SUPPLY VOLTAGE (V)
10 5.4 5.6
5511 G24
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LT5511 TYPICAL PERFOR A CE CHARACTERISTICS
Table 1. Typical S-Parameters for the IF, RF and LO Ports (referenced to 50). VCC = 5VDC, EN = High , TA = 25C. For each Port Measurement, the other Ports are Terminated as Shown in Figure 2.
Frequency (MHz) 10 50 100 150 200 250 300 350 400 450 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 Differential IF Port Mag. 0.65 0.648 0.645 0.627 0.626 0.619 0.617 0.609 0.597 0.586 0.567 0.527 0.484 0.438 0.451 0.554 0.581 0.574 0.567 0.557 0.540 0.520 0.495 0.462 0.432 0.405 0.390 0.366 0.310 0.417 0.489 0.491 0.472 0.445 0.412 0.375 Ang. 179.2 176.2 173.3 170.6 168.5 166.7 165.0 164.1 162.7 162.2 161.3 160.6 160.0 160.6 167.8 162.3 150.0 141.4 137.2 135.1 135.6 136.5 136.9 135.3 131.0 124.4 116.1 108.1 110.2 127.5 121.5 122.0 126.7 132.0 138.9 142.4 Differential RF Port Mag. - 0.644 0.643 0.642 0.642 0.639 0.635 0.632 0.629 0.626 0.623 0.622 0.620 0.617 0.615 0.613 0.611 0.607 0.602 0.594 0.585 0.576 0.567 0.557 0.548 0.540 0.529 0.521 0.513 0.503 0.495 0.486 0.479 0.472 0.468 0.463 Ang. - -0.8 -2.0 -3.0 -4.0 -5.0 -6.1 -7.2 -8.3 -9.5 -10.7 -13.0 -15.4 -18.0 -20.3 -22.4 -24.6 -26.6 -28.6 -30.7 -32.9 -35.3 -37.8 -40.7 -43.8 -47.0 -50.2 -53.9 -57.4 -61.4 -65.3 -69.0 -73.2 -76.8 -80.4 -83.1 Differential LO Port Mag. - 0.814 0.836 0.804 0.823 0.803 0.815 0.806 0.804 0.805 0.798 0.797 0.799 0.804 0.808 0.814 0.817 0.813 0.811 0.805 0.795 0.790 0.789 0.791 0.793 0.795 0.796 0.796 0.790 0.782 0.765 0.748 0.731 0.721 0.720 0.722 Ang. - -0.6 -0.8 -1.0 -1.6 -1.8 -2.5 -2.9 -3.8 -4.4 -5.2 -6.6 -7.8 -8.9 -9.6 -10.2 -10.7 -11.2 -12.2 -13.7 -15.6 -18.0 -20.6 -22.9 -24.8 -26.2 -27.3 -28.4 -29.8 -31.8 -34.8 -38.8 -43.3 -48.3 -52.5 -55.9 Single LO Port Mag. - 0.788 0.808 0.780 0.789 0.779 0.773 0.777 0.760 0.776 0.749 0.746 0.750 0.753 0.756 0.763 0.765 0.755 0.751 0.743 0.731 0.727 0.726 0.728 0.728 0.728 0.724 0.718 0.703 0.687 0.668 0.656 0.652 0.663 0.680 0.701 Ang. - -1.0 -1.5 -2.1 -3.0 -3.7 -4.7 -5.9 -7.2 -8.9 -10.0 -12.9 -15.7 -18.0 -19.5 -20.5 -21.6 -22.7 -24.7 -27.7 -31.2 -35.3 -39.3 -42.6 -45.0 -46.7 -48.0 -49.8 -52.4 -56.5 -62.7 -70.5 -78.7 -85.9 -91.2 -94.2
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PI FU CTIO S
LO-, LO+ (Pins 1, 16): Differential Inputs for the Local Oscillator Signal. They can also be driven single-ended by connecting one to an RF ground through a DC blocking capacitor. For single-ended drive, use LO+ for the signal input, as this results in less interference from unwanted coupling of the LO signal to other pins. These pins are internally biased to about 1.4V; thus, DC blocking capacitors are required. An impedance transformation is required to match the LO input to 50 (or 75). At frequencies below 1.5GHz this input can be resistively matched with a shunt resistor. NC (Pins 2, 9): Not Connected Internally. Connect to ground for improved isolation between pins. GND (Pins 3, 6, 8,11, 14): Internal Grounds. These pins are used to improve isolation and are not intended as DC or RF grounds for the IC. Connect these pins to ground for best performance. IF+, IF - (Pins 4, 5): Differential Inputs for the IF Signal. A differential signal must be applied to these pins. These pins are internally biased to about 1.2V, and thus require DC blocking capacitors. These pins should be DC isolated from each other for best LO suppression. Imbalances in amplitude or phase between these two signals will degrade the linearity of the mixer. VCCBIAS (Pin 7): Supply Voltage for the LO Buffer Bias and Enable Circuits. This pin should be connected to VCC and have appropriate RF bypass capacitors. Care should be taken to ensure that RF signal leakage to the VCC line is minimized. EN (Pin 10): Chip Enable/Disable. When the applied voltage is greater than 3V, the IC is enabled. When the applied voltage is less than 0.5V, the IC is disabled and the DC current drops to about 1A. Under no conditions should the voltage on this pin exceed VCC + 0.3V, even at power on. RF -, RF+ (Pins 12, 13): Differential Outputs for the RF Output Signal. An impedance transformation may be required to match the outputs. These pins are also used to connect the mixer to the DC supply through impedancematching inductors, RF chokes or transformer center-tap. Care should be taken to ensure that the RF signal leakage to VCCLO and VCCBIAS is minimized. VCCLO (Pin 15): Supply Voltage for the LO Buffer Amplifier. This pin should be connected to VCC and have appropriate RF bypass capacitors. Care should be taken to ensure that RF signal leakage to the VCC line is minimized. GROUND (Backside Contact) (Pin 17): DC and RF Ground Return for the Entire IC. This contact must be connected to a low impedance ground plane for proper operation.
BLOCK DIAGRA
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LO- 1
LO+ 16
NC
2
15 VCCLO 14 GND LO BUFFER 13 RF+
GND 3 IF+ 4
IF -
5 BIAS CIRCUITS 8 GND 17 9
12 RF - 11 GND 10 EN GND NC (BACKSIDE)
GND 6 VCCBIAS 7
5511 BD
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TEST CIRCUIT
LO R1 C1 C7 1 2 IF C8 5 4 4x T1 3 1x 1 C13 VCC C17 C10 R2 C11 R3 3 4 5 6 7 8 LO- NC GND IF+ IF - GND VCCBIAS GND EXPOSED PAD GND
5511F02
VCC C5 C4
VCC
LT5511 LO+ VCCLO GND RF+
16 15 14 13 T2 L1 C12 2 1 L2 R5 EN C14 4x 1x 5 3 4 C15 C9 RF
12 RF - GND EN NC 11 10 9
Component C1, C9, C11, C15 C5, C7, C17 C4 C8 C10, C12, C13 C14 L1, L2 R1 R2, R3 R5 T1 T2
Value 22pF 100pF 0.1F 220pF 1000pF 1.5pF 6.8nH 62 75, 0.1% 10k 4:1 4:1
Comments 0402 0402 0402 0402 0402 0402 0402 0402 0603 0402 Coilcraft TTWB-4-A M/A-Com ETC1.6-4-2-3
Figure 2. Test Circuit and Evaluation Board Schematic for 950MHz Application.
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TEST CIRCUIT
LO C1
C2 L3 C7 1 2 IF C8 5 4 4x T1 3 1x 1 C13 VCC C17 C10 R2 C11 R3 3 4 5 6 7 8 LO- NC GND IF+ IF - GND VCCBIAS GND EXPOSED PAD GND LT5511 LO+ VCCLO GND RF+ RF - GND EN NC 16 15 14 13 12
VCC C5 C4
VCC
T2 L1 C12 2 1 4x 1x 5 3 4 C15 L4 C9 RF
11 10 9 R5
L2 EN
5511 F03
Component C1, C9, C11, C15 C5, C7, C17 C4 C8 C10, C12, C13 C2 L3 L1, L2 L4 R2, R3 R5 T1 T2
Value 22pF 100pF 0.1F 220pF 1000pF 1.2pF 6.8nH 4.7nH 1.8nH 75, 0.1% 10k 4:1 4:1
Comments 0402 0402 0402 0402 0402 0402 0402 0402 0402 0603 0402 Coilcraft TTWB-4-A M/A-Com ETC1.6-4-2-3
Figure 3. Test Circuit and Evaluation Board Schematic for 1.9GHz Application.
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APPLICATIO S I FOR ATIO
The LT5511 consists of a double-balanced mixer driven by a high-performance, differential, limiting LO buffer. The mixer has been optimized for high linearity and high signal level operation. The LT5511 is intended for applications with LO frequencies of 0.4GHz to 2.7GHz and IF input frequencies from 10MHz to 300MHz, but can be used at other frequencies with excellent results. The LT5511 can be used in applications using either a low side or high side LO. LO Input Port The LO buffer on the LT5511 consists of differential high speed amplifiers and limiters that are designed to drive the mixer quad to achieve high linearity and performance at high IF input signal levels. The LO+ and LO- pins are the differential inputs to the LO buffer. Though the LO signal can be applied differentially, the LO buffer performs well with only one input driven, thus eliminating the need for a balun. In this case, a capacitor should be connected between the unused LO input pin and ground. The LO pins are biased internally to about 1.4V, and thus must be DC isolated from the external LO signal source. The LO input should be matched to 50. The impedance match can be accomplished through the use of a reactive impedance matching network. However, for lower LO frequencies (below about 1.5GHz), an easier approach is to use a shunt 62 resistor to resistively match the port. (The resistor must be DC isolated from the LO input pin). This method is broadband and requires LO power levels of only -10dBm. At higher frequencies, a better match can be realized with reactive components. Transmission lines and parasitics should be considered when designing the matching circuits. Typical S-parameter data for the LO input is included in Table 1 to facilitate the design of the matching network.
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IF Input Port The IF+ and IF- pins are the differential inputs to the mixer. These inputs drive the emitters of the switching transistors, and thus have a low impedance. The DC current through these transistors is set by external resistors from each IF pin to ground. The typical internal voltage on the emitters is 1.2V; thus, the current through each IF pin is approximately: IIF = 1.2/RIF RIF is the value of the external resistors to ground. Best performance is obtained when the IF inputs are perfectly balanced and 0.1% tolerance resistors are recommended here. The LT5511 has been characterized with 75 resistors on each of the IF inputs. The IF signal to the mixer must be differential. To realize this, an RF balun transformer or lumped element balun can be used. The RF transformer is recommended, as it is easier to realize broadband operation, and also does not have the component sensitivity issues of a lumped element balun. The differential input impedance of the IF input is approximately 12.5; therefore, a 4:1 impedance transformation is required to match to 50. Selecting a transformer with this impedance ratio will reduce the amount of additional components required, as the full impedance transformation is realized by the transformer. DC-isolating transformers or transmission-line transformers can be used, as could lumped element transformation networks. Because the IF ports are internally biased, they must be DC isolated from the IF source. Additionally, IF+ and IF- must be DC isolated from each other in order to maintain good LO suppression.
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LT5511
APPLICATIO S I FOR ATIO
On the evaluation board (Figure 4), 1nF DC-blocking capacitors are used on the IF input pins. A 220pF capacitor on the 50 source side of the input balun is used to tune out the excess inductance to improve the match at 50MHz. To shift the match higher in frequency, this capacitor value should be reduced. RF Output Port The RF outputs, RF+ and RF-, are internally connected to the collectors of the mixer switching transistors. These differential output signals should be combined externally through an RF balun transformer or 180 hybrid to achieve
(4a) Top Layer Silkscreen Figure 4. Evaluation Board Layout.
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optimum performance. These pins are biased at the supply voltage, which can be applied through the center tap of the output transformer. (The center tap should be RF bypassed for best performance). A pair of series inductors can be used to match RF+ and RF- to the high impedance (200) side of a 4:1 balun. The output balun has a significant impact on the performance of the mixer. A broadband balun provides better rejection of the 2fLO spur. If the level of that spur is not critical, a less expensive and smaller balun can be used. The amplitude and phase balances of the balun will affect the LO suppression.
(4b) Top Layer Metal
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LT5511
APPLICATIO S I FOR ATIO
10dB PAD LO SIGNAL GENERATOR 3 LOIN
RF SIGNAL GENERATOR 1
RF SIGNAL GENERATOR 2
Figure 5. Test Set-Up for Mixer Measurements
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SPECTRUM ANALYZER POWER SUPPLY RFOUT GND T2 E3 LT5511 IC T1 IFIN E2 DMM E1
SW1
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+
POWER SUPPLY (OR PULSE GENERATOR FOR TURN-ON AND TURN-OFF MEASUREMENTS)
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LT5511
TYPICAL APPLICATIO S
LO C1
C10 IF + (50) C13 IF - (50) C2
VCC C18
Component C1, C9 C5, C7, C18 C4 C2 C10, C12, C13 C11 L1 L6, L7 R2, R3 R5 T2 Transmission Lines TL1, TL2
Figure 6. Test Circuit Schematic for 2.4GHz RF Application with 300MHz IF Input Frequency
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L6 L7
C11 L1 C7 1 2 3 R2 4 5 R3 6 7 8 LO- NC GND IF+ IF - GND VCCBIAS GND EXPOSED PAD GND LT5511 LO+ VCCLO GND RF+ RF - GND EN NC 16 15 14 13
VCC C5 C4
VCC
TL1 C12
3
T2
C9 1
RF
2
12 11 10 9 R5 TL2 EN 4 5
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Value 22pF 100pF 0.1F 12pF 1000pF 1pF 5.2nH 5.6nH 75, 0.1% 10k 1:1 ZO = 80
Comments 0402 0402 0402 0402 0402 0402 0402 0402 0603 0402 MURATA LDB15C500A2400 L = 16 AT 2.4GHz
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LT5511
TYPICAL APPLICATIO S
Conversion Gain and LO to RF Leakage vs Output Frequency (Figure 6)
0 -1 -2 -3 GAIN fIF1 = 300MHz AT -8dBm fIF2 = 301MHz AT -8dBm PLO = -10dBm fLO SWEPT FROM 1900MHz TO 2300MHz -8 -13 -18 -23 -28 -33 -38 -43 LO LEAKAGE -48 -53 2300 2500 2400 RF OUTPUT FREQUENCY (MHz) -58 2600
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IIP3, IIP2 (dBm)
GAIN (dB)
-4 -5 -6 -7 -8 -9
-10 2200
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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IIP3 and IIP2 vs Output Frequency (Figure 6)
50 45 40 35 30 25 20 15 10 5 0 2200 2300 2500 2400 RF OUTPUT FREQUENCY (MHz) 2600
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IIP2
LO TO RF LEAKAGE (-dBm)
fIF1 = 300MHz AT -8dBm fIF2 = 301MHz AT -8dBm PLO = -10dBm fLO SWEPT FROM 1900MHz TO 2300MHz IIP3
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LT5511
PACKAGE DESCRIPTIO
2.74 (.108)
6.60 0.10 4.50 0.10 SEE NOTE 4
0.65 BSC RECOMMENDED SOLDER PAD LAYOUT 4.30 - 4.50* (.169 - .177) 0 - 8 12345678 1.10 (.0433) MAX
0.09 - 0.20 (.0036 - .0079)
0.45 - 0.75 (.018 - .030)
NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) 3. DRAWING NOT TO SCALE
RELATED PARTS
PART NUMBER LT5500 LT5502 LT5503 LT5504 LTC(R)5505 LT5506 LT5507 LTC5508 LT5512 DESCRIPTION 1.8GHz to 2.7GHz Receiver-Front End 400MHz Quadrature IF Demodulator with RSSI 1.2GHz to 2.7GHz Direct IQ Modulator and Upconverting Mixer 800MHz to 2.7GHz Measuring Receiver RF Power Detectors with >40dB Dynamic Range 500MHz Quadrature Demodulator with VGA 100kHz to 1GHz RF Power Detector 300MHz to 7GHz RF Power Detector High Signal Level Down Converting Mixer COMMENTS 1.8V to 5.25V Supply, Dual-Gain LNA, Mixer, LO Buffer 1.8V to 5.25V Supply, 70MHz to 400MHz IF, 84dB Limiting Gain, 90db RSSI Range 1.8V to 5.25V Supply, Four-Step RF Power Control, 120MHz Modulation Bandwidth 80dB Dynamic Range, Temperature Compensated, 2.7V to 5.5V Supply 300MHz to 3GHz, Temperature Compensated, 2.7V to 6V Supply 1.8V to 5.25V Supply, -4dB to 57dB Linear Power Gain 48dB Dynamic Range, Temperature Compensated, 2.7V to 6V Supply >40dB Dynamic Range, SC70 Package Up to 3GHz, 20dBm IIP3, Integrated LO Buffer
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507
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FE Package 16-Lead Plastic TSSOP (4.4mm)
(Reference LTC DWG # 05-08-1663)
Exposed Pad Variation BA
4.90 - 5.10* (.193 - .201) 2.74 (.108) 16 1514 13 12 1110 9
2.74 (.108) 0.45 0.05 1.05 0.10 2.74 6.40 (.108) BSC
0.65 (.0256) BSC
0.195 - 0.30 (.0077 - .0118)
0.05 - 0.15 (.002 - .006)
FE16 (BA) TSSOP 0203
4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE
LT/TP 0503 1K * PRINTED IN USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2001

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