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WIRELESS COMMUNICATIONS DIVISION
GND/LNA Gain GND/LNA Gain Mixer Vdd
TQ5635
DATA SHEET
LNA Out
1 GND
Active Bias MXR In
3 V PCS LNA/Mixer Receiver IC
RF In
LNA
GND
Mixer GND LO Vdd
Features
? Single 3.0 V Operation ? ? Adjustable Gain/IP3/Current ? ? Low Current Operation ? ? Few external components ? ? QFN 3x3 mm, 16 Pin Leadless Plastic ? Package ? High Input IP3 ? ? Low Noise Figure ?
LNA Bias
active bias
LO Buffer IF Amp
LO In
LNA Vdd
GND
IF Out
GIC
Product Description
The TQ5635 is an LNA-Downconverter optimized for use in the Korea CDMA PCS bands. The integrated LNA has a single high gain mode that provides over 15 dB of gain, and features very low NF and excellent IP3. An external resistor controls LNA bias, making LNA Idd adjustable. The integrated mixer features very high IP3 and provision for external adjustment of gain, IP3, and Idd. Because of the external LO tuning inductor, IF's in the range of 85 to 200Mhz can be used. The excellent RF performance with low current coupled with very small lead-less plastic package is ideally suited for PCS band mobile phone.
Applications
? PCS band CDMA mobile Applications ? ? Wireless data applications ?
Electrical Specifications 1
Parameter RF Frequency Conversion Gain Noise Figure Input 3rd Order Intercept DC supply Current
Note 1. Test Conditions:
Min
Typ 1855 24.5 2.3 -4.75 23.4
Max
Units MHz dB dB dBm mA
Vdd=+2.8V, TC=+25C, RF=1855MHz, RF in =-30dBm LO=1635MHz, LO input=-4dBm, IF=220MHz 2. Data includes image reject filter (Sawtek P/N: 356083) insertion loss of 1.7 dB
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1
TQ5635 Data Sheet
Absolute Maximum Ratings
Parameter Storage Temperature Case Temperature w/bias Supply Voltage Voltage to any non supply pin Power Dissipation Signal Power Symbol Tstore Tc VDD P Ps Minimum -40 -40 0 Nominal 25 25 2.8 Maximum 125 85 5.0 100 20 Units deg. C deg. C V VDD+0.5V mW dBm
Note 1. All voltages are measured with respect to GND (0V), and they are continuous. 2. Absolute maximum ratings as detailed in this table, are ratings beyond which the device's performance may be impaired and/or permanent damage may occur.
Typical Electrical Characteristics -Korea PCS band, Cascade
Parameter RF Frequency IF Frequency LO input level2 -7 Supply voltage Conversion Gain Noise Figure1,4 Input 3rd Order Intercept1,3,4 Supply Current2,3
Note 1. 2. 3. 4.
1,3,4
Conditions
Min. 1840
Typ/Nom
Max. 1870
Units MHz MHz dBm V dB
220 -4 2.8 21.5 -6.5 24.5 2.3 -4.75 23.4 25.0 2.8 -1
dB dBm mA
Test Conditions (devices screened for Conversion Gain, Noise Figure, and IIP3 to the above limits): Vdd = +2.8V, RF = 1855MHz, LO = 1635MHz, IF = 220MHz, LO input = -4dBm, RF input = -30dBm, TC = +25? C, unless otherwise specified. Min./Max. limits are at +25? C case tempera ture unless otherwise specified. Conversion Gain and Idd depends on the values of the two resistors used in the GIC circuit and LNA Bias resistor. Data includes image reject filter (Sawtek P/N: 356083) insertion loss of 1.7 dB
2
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TQ5635 Data Sheet
Typical Electrical Characteristics - Korea PCS band, LNA only:
Parameter RF Frequency Conversion Gain Noise Input Figure1 Order Intercept1,3 Current3
Min./Max. limits are at +25? C case temperature unless otherwise specified. Conversion Gain and Idd depends on the values of the Bias resistor.
1,3
Conditions
Min. 1840
Typ/Nom
Max. 1870
Units MHz dB dB dBm mA
17.5 1.8 1.1 7.0
3rd
Supply
2. 3.
Note 1. Test Conditions: Vdd = +2.8V, RF = 1855MHz, LO = 1635MHz, IF = 220MHz, LO input = -4dBm, RF input = -30dBm, TC = +25?C, unless otherwise specified.
Typical Electrical Characteristics - Korea PCS band, Mixer only:
Parameter RF Frequency IF Frequency Conversion Gain Noise Input Figure1 Order Intercept1,3 Current3
Min./Max. limits are at +25? C case temperature unless otherwise specified. Conversion Gain and Idd depends on the values of the two resistors used in the GIC circuit. Data includes image reject filter (Sawtek P/N: 356083) insertion loss of 1.7 dB
1,3
Conditions
Min. 1840
Typ/Nom
Max. 1870
Units MHz MHz dB dB dBm mA
220 9.1 8.2 11.6 16.5
3rd
Supply
2. 3. 4.
Note 1: Test Condition: Vdd = +2.8V, RF = 1855MHz, LO = 1635MHz, IF = 220MHz, LO input = -4dBm, RF input = -30dBm,TC = +25?C, unless otherwise specified..
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3
TQ5635 Data Sheet
Typical Test Circuit for CDMA KPCS:
Test Conditions (Unless Otherwise Specified): Vdd = +2.8V, RF = 1855MHz, LO = 1635MHz, IF = 220MHz, LO input = -4dBm, RF input = -30dBm, TC = +25?C
B+ NC AUXin
C11 Vdd Vdd R8 C6 F1
LNA Mode
LNA Out
MX VD D
GND
RFin
L1
L4
GND
MXR In
RF In
GND
C7
C8 Vdd
TQ5635
C5
GND
V DD IF Bias IF Out LO In
LOin
L2 R6
R7
GND
LNA Bias V DD
C10 Vdd R9 C9 R16 R12 L3 C14 C13 C15
TOKO TOKO 0603
IFout
RL 021401
Bill of Material for TQ5635 LNA/Downconverter Mixer for GIC tuning plots
Component Receiver IC Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor Inductor Inductor Inductor Inductor Resistor Resistor Resistor C11, C13 C5 C6 C7 C8, C9, C10,C13 C14 C15 L1 L2 L3 L4 R8, R16 R6 R7 * LNA Bias Reference Designator Part Number TQ5635 0.1uF 2.2pF 1.0pF 1000pF 1000pF 15pF 12pF 3.9nH 5.6nH 56nH 3.3nH 3.3O 20O 2.7KO Value Size 3x3mm 0402 0402 0402 0402 0402 0402 0402 0402 0402 0603 0402 0402 0402 0402 Coil Craft TOKO TOKO TOKO Manufacturer TriQuint Semiconductor
4
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TQ5635 Data Sheet
Resistor Resistor RF Saw Filter R9 R12 F1 * GIC 856083 1.8O 39O 0402 0402 2x2mm SAWTEK
CDMA KPCS Band Typical LNA Performance
Test Conditions (Unless Otherwise Specified): Vdd=+2.8V, Tc=+25C, RF = 1852MHz, LO = 1635MHz, I F = 220MHz
Conversion Gain vs Vdd vs Temp
20
Conversion Gain vs Vdd vs Freq
19 18.5 18 17.5 17 16.5 16 1830
Conversion Gain (dB)
19
18
17
Conversion Gain (dB)
16
-40C
15 2.5 2.7 2.9
25C
3.1 3.3
85C
3.5 1840
2_7V 3_2V
1850 1860
2_8V 3V
1870 1880
Vdd (V)
Conversion Gain vs Vdd vs Temp
20
RF Freq (MHz)
Input IP3 vs Vdd vs Temp
3
Conversion Gain (dB)
19
2
18
IP3 (dBm)
-40C 25C
3.1 3.3
1
17
16
0
85C
3.5
-40C
-1 2.5 2.7 2.9
25C
85C
3.3 3.5
15 2.5 2.7 2.9
Vdd (V)
Vdd (V)
3.1
Input IP3 vs Temperature vs Freq
2
9
Idd vs Vdd vs Temperature
1.5
8
IP3 (dBm)
1
Idd (mA)
-40C 25C
1850 1860 1870
7
0.5
6
85C
1880
5 2.5 2.7
-40C
2.9
25C
3.1 3.3
85C
3.5
0 1830
1840
RF Freq (MHz)
Vdd (V)
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5
TQ5635 Data Sheet
Idd vs Temperature vs Frequency
9
Noise Figure vs Temp vs Frequency
2.5
Noise Figure (dB)
8
2.1
Idd (mA)
1.7
7
1.3
6
0.9
-40C
5 1830 1840 1850
25C
1860
85C
1870 1880
-40C
0.5 1830 1840 1850
25C
1860 1870
85C
1880
RF Freq (MHz)
RF Freq (MHz)
Noise Figure vs Vdd vs Temp
2.5
2.1
Noise Figure (dB)
1.7
1.3
0.9
-40C
0.5 2.5 2.7 2.9
25C
3.1 3.3
85C
3.5
Vdd (V)
6
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TQ5635 Data Sheet
CDMA KPCS Band Typical Mixer Performance
Test Conditions (Unless Otherwise Specified): Vdd=+2.8V, Tc=+25C, RF = 1852MHz, LO = 1635MHz, I F = 220MHz, LO input = 4dBm
Gain vs Vdd vs Temperature
13
Gain vs Vdd vs Frequency
11
Conversion Gain (dB)
11 10 9 8
Conversion Gain (dB)
12
10.5 10 9.5 9 8.5 8 1830
-40C
7 2.5 2.7 2.9 3.1
25C
3.3
85C
3.5 3.7
2_7V 3_5V 1840 1850 1860
2_8V 3V 1870 1880
Vdd (V)
Gain vs Temperature vs Frequency
13
RF Freq (MHz)
Conversion Gain vs LO vs Freq
10
Conversion Gain (dB)
12 11 10 9 8 7 1830
Conversion Gain (dB)
9.5
9
8.5 -1dBm 8 1830 -4dBm -7dBm
-40C
1840 1850
25C
1860 1870
85C
1880
1840
1850
1860
1870
1880
RF Freq (MHz)
RF Freq (MHz)
Input IP3 vs Temp vs Frequency
14 13 12
Input IP3 vs Vdd vs Temperature
14 13 12 11 10 9 8 2.5 2.7 2.9 3.1 3.3 3.5 3.7
IP3 (dBm)
IP3 (dBm)
-40C 25C 85C
11 10 9 8 7 1830
-40C
1840 1850
25C
1860
85C
1870 1880
Vdd (V)
RF Freq (MHz)
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7
TQ5635 Data Sheet
Input IP3 vs LO Drive vs Frequency
12.3 22
Idd vs Vdd vs Temperature
11.9
20
IP3 (dBm)
Idd (mA)
11.5
18
11.1
16
10.7 -1dBm 10.3 1830 -4dBm -7dBm
14
-40C
12 2.5 2.7 2.9 3.1
25C
3.3
85C
3.5 3.7
1840
1850
1860
1870
1880
RF Freq (MHz)
Vdd (V)
Noise Figure vs Vdd vs Temp
10 9
Idd vs Temperature vs Frequency
19
18
Noise Figure (dB)
8 7 6 5
Idd (mA)
17
16
15
-40C
2.5 2.7 2.9 3.1
25C
3.3
85C
3.5 3.7
-40C
14 1830 1840 1850
25C
1860
85C
4 1870 1880
RF Freq (MHz)
Vdd (V)
Noise Figure vs Temp vs Frequency
11
Noise Figure (dB)
9
7
5
-40C
3 1830 1840 1850
25C
1860
85C
1870 1880
RF Freq (MHz)
8
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TQ5635 Data Sheet
CDMA KPCS Band Typical Cascade Performance
Test Conditions (Unless Otherwise Specified): Vdd=+2.8V, Tc=+25C, RF = 1852MHz, LO = 1635MHz, I F = 220MHz, LO input = -4dBm
Gain vs LO vs Frequency
28
Gain vs Vdd vs Temperature
28
Conversion Gain (dB)
26
24
22
Conversion Gain (dB)
26
24
22 -1dBm 20 1830 -4dBm -7dBm
-40C
20 2.5 2.7 2.9
25C
3.1 3.3
85C
3.5
1840
Vdd (V)
RF Freq (MHz)
1850
1860
1870
1880
IIP3 vs Vdd Vs Frequency
Gain vs Vdd vs Frequency
29
-3
-4
Conversion Gain (dB)
27
IIP3 (dBm)
-5
25
-6 2_7 3 -7 1830 1840 1850 1860 2_8 3_2 1870 1880
23 2_7V 3_2V 2_8V 3V
21 1830
1840
RF Freq(MHz)
1850
1860
1870
1880
Frequency (MHz) IP3 vs Vdd vs Temperature
Gain vs Temperature vs Frequency
29
-2 -3 -4 -5 -6 -7
Conversion Gain (dB)
25
23
IP3 (dBm)
27
21
-40C
2.5 2.7 2.9
25C
3.1 3.3
85C
3.5
-40C
19 1830 1840 1850
25C
1860
85C
1870 1880
-8
Vdd (V)
RF Freq (MHz)
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9
TQ5635 Data Sheet
IP3 vs Temperature vs Freq
0 5
Noise Figure vs Vdd vs Temp
-2
Noise Figure (dB)
4
IP3 (dBm)
-4
3
-6
2
-8
1
-40C
-10 1830 1840 1850
25C
1860 1870
85C
0 1880 2.5 2.7
-40C
2.9
25C
3.1 3.3
85C
3.5
RF Freq (MHz)
Vdd (V)
Noise Figure vs Temp vs Freq
5
IP3 vs LO Drive vs Frequency
-3 -4 -5 -6 -7 -8 -9 1830
4
Noise Figure (dB)
-1dBm -4dBm -7dBm
IP3 (dBm)
3
2
1
-40C
1880 0 1830 1840 1850
25C
1860
85C
1870 1880
1840
1850
1860
1870
RF Freq (MHz)
Noise Figure vs LO vs Frequency
28
2.6 2.5
RF Freq (MHz)
Idd vs Vdd vs Temperature
26
Noise Figure (dB)
Idd (mA)
2.4 2.3 2.2
24
22
20
2.1 2 1830
-40C
25C
85C
-1
1840 1850
-4
1860
-7
18
1870 1880
2.5
2.7
2.9
3.1
3.3
3.5
Frequency (MHz)
Vdd (V)
10
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TQ5635 Data Sheet
Idd vs Temperature vs Frequency
26 25 24
Idd (mA)
23 22 21 20 1830
-40C
1840 1850
25C
1860
85C
1870 1880
RF Freq (MHz)
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11
TQ5635 Data Sheet
Pinout Description:
The TQ5635 is a complete front-end for a Korea high band CDMA handset receiver. It combines a high IP3 low noise amplifier, a high intercept mixer, and an IF amplifier. The LNA uses an off-chip matching network which connects to the input at pin 2. The amplifier was designed so that the match for maximum gain also gives very low noise figure. The LNA has a single high gain mode that typically provides 15-16dB of gain. The LNA also provides several ways of setting gain and intercept in the design phase. The LNA FET source is brought out to Pins 15 and 16, where a small value of inductance to ground can be added. The inductor can be discrete or simply a small length of pc board trace. Several dB of adjustment is possible. For most applications, maximum gain will be desired. In that case, pins 15 and 16 should be connected to ground with multiple vias. A bias resistor on pin 4 is used to set the LNA supply current. A nominal value of 2.7kohm is recommended. The LNA output signal is at Pin 14. It is a 50 ohm line and can be connected directly to a SAW image filter. The image filter output connects to the mixer input at Pin 12. The mixer receives its LO via a buffer which amplifies the signal from Pin 9. The buffer transistor drain comes out of Pin 10 where it connects to an external LO tuning inductor.
GND/LNA Gain GND/LNA Gain LNA Out Mixer Vdd
The IF signal from the mixer is fed to an amplifier. The IF amplifier is an open drain type with output at Pin 7. An external matching circuit is required to match the IF output to a filter. The IF amplifier also has a GIC pin (Gain-InterceptCurrent). It is used to set the DC current and gain of the IF stage.
Application Information: Half IF Spur Rejection Considerations:
The TQ5635 has a single ended mixer so Half-IF spur rejection is set by the image filter. Thus we do not recommend using an IF that is less than 2.5 times the image filter.
Grounding:
With good layout techniques there should not be any stability problems. Poor circuit board design can result in a circuit that oscillates. Good grounding is especially important for the TQ5635 since it uses an outboard LO tuning inductor that provides one more potential ground loop path. One could use the evaluation board as an example of proper layout techniques. It is important to position the LO tuning, GIC, and IF matching components as close to the chip as possible. If the components are far enough away they and their corresponding pc board traces can act as quarter wave resonators in the 5-10Ghz region. If both the IF and the LO paths to ground resonate at the same frequency, oscillation can result.
1 GND
Active Bias MXR In
It is most important that the ground on the GIC bypass cap, the ground on the LO tuning bypass capacitor, and the IF shunt cap ground return back to the chip grounds with minimal inductance (Figure 2).
RF In
LNA
GND
Mixer GND LO Vdd
Also, improving the ground at the LO tuning inductor bypass cap will increase circuit Q. Thus mixer drive is improved with a resultant higher IP3. Improved ground here means minimal inductance between the chip ground pins and the other ground return points. Although it is not a stability issue, proper grounding of pins 15 and 16 is necessary for maximum LNA gain. Multiple vias to ground should be placed very close to those pins.
LNA Bias
active bias
LO Buffer IF Amp
LO In
LNA Vdd
GND
IF Out
GIC
Figure 1. TQ5635 Block diagram
12
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TQ5635 Data Sheet
Use multiple ground vias for maximum LNA gain
Figure 3 shows a much simplified block diagram of the LNA, image filter, and mixer. The RF signal is amplified by the LNA, passes through the image filter, and is converted down to the IF where it is amplified by the IF output FET. The quiescent current in the IF amplifier is set by the GIC network. Both the filter and the mixer terminate the RF signal with 50ohms.
Vdd
GND
LNA Out
GND
GND
RF In
GND
TQ5635
VDD MXR In GND VDD IF Bias LO In
GND
IF Out
VDD
LNA Bias
However, the situation is much different with the LO signal. At the LO frequency the image filter looks like a short circuit. Some LO energy leaks out of the mixer input, bounces back off of the image filter and returns back into the mixer with some phase or delay. The delayed LO signal mixes with the normal LO to create a DC offset in the passive FET. A DC
Vdd IFout Minimize These Lengths
Figure 2. Critical signal Paths
blocking capacitor prevents the offset voltage from affecting IF stage current. It has been found empirically that varying the delay between
Mixer - Filter Interaction:
Before attempting a new TQ5635 application, it is important to understand the nonlinear interaction between the image filter and the mixer subcircuit. The device IP3 is a strong function of this interaction. For this reason it is helpful to consider the filter and mixer as one nonlinear block.
25-100 ohms at RFshort circuit at LO
the filter and mixer can have positive or negative consequences on IP3, CG, and NF. It is for this reason that an LC network is useful between the SAW and mixer input, even though the mixer input can have an adequate match at the RF frequency without any external components.
LNA Portion of TQ5635
LNA Out
Mixer Portion of TQ5635
IF Output FET
Blocking Cap
LO Leakage
12
RF in
Mixer
IF Output
7
2
14
Mixer in
Idd IF + DC Offset IF
band pass
LO Leakage ?????? LO
9
to GIC
8
(LO Leakage ?????+ LO) = DC Offset at Mixer IF Output
Figure 3. Non-linear filter-Mixer Interaction
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13
TQ5635 Data Sheet
LNA S-Parameters :
S-Parameters for the TQ5635 LNA taken in the high mode. We have not included noise parameters since for this device Gamma-Opt is very close to the conjugate match.
Figure 4: LNA S11
Figure 6: LNA S21
Figure 5: LNA S12
Figure 7: LNA S22
14
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TQ5635 Data Sheet
SUGGESTED STEPS FOR TQ5635 TUNING:
The following order of steps is recommended for applying the TQ5635. They are described in detail in the following sections: Lay out board consistent with the grounding guidelines at the beginning of this note. See section 1 regarding LNA source inductor. 1. Determine the LNA bias resistor value and source inductor value 2. Determine the LNA input matching network component values. Test the LNA by itself. 3. For the mixer, experimentally determine proper LO tuning components. This step needs to be done first since all of the later tuning is affected by it. 4. Determine a tentative GIC network. It will have to be finetuned later, since the image filter interaction will affect device current. 5. Synthesize a tentative IF output match. It may have to be fine-tuned later, as the final GIC configuration affects IF stage current. LO is turned ON. 6. Experimentally determine a tentative mixer RF Input match. LO is turned ON. Test the filter-mixer cascade. Verify that the device has adequate IP3. If not, another RF Input matching topology can be tried. 7. Fine tune GIC components for needed Idd. LO is turned ON. 8. Check IF match to see if it still is adequate. LO is turned ON. 9. Test the device as a whole - LNA, filter, mixer Figure 8: Gain, IIP3, Idd, and NF as a Function of Rbias
dB 18 16 14 12 10 8 6 4 2 0 1.1 1.5 2.2 2.7 3.3 4.7 6.8 8.2 10 Idd (mA) 12 11 10
1. Determine LNA Bias Resistor Value and Source Inductor Value For most designs we recommend an LNA bias resistor of 2.7K ohms. All of the datasheet specs assume that value of resistor. However, if LNA Idd < 7.5 mA is desired, then the resistor can be made larger. Refer to Figure 8 for graphs of LNA performance vs. bias resistor. Please keep in mind that there are implications of reduced LNA bias that are not reflected in IP3. For example, the LNA is normally in front of the image filter so that it may need resistance to blocking or other types of distortion that are not adequately described by the IP3 figure of merit.
5635 LNA NF, Gain, IIP3 and Idd vs bias resistor
NF IIP3
Gain Idd
9 8 7 6 5 4 3
Bias resistor (kOhms)
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15
TQ5635 Data Sheet
For most applications needing maximum LNA gain, it will probably be sufficient to simply ground pins 15 and 16 as shown in the second diagram in Figure 9. However, in some cases a small amount of inductance may be needed from pins 15 and 16 to ground in order to lower the LNA gain. Because of stray inductance on the application board layout, it is difficult to give a precise value of L as a function of gain reduction. The first diagram in Figure 9 illustrates one way of doing this. A short is placed across the inductor until the needed gain is arrived at. 3. LO Buffer Tuning The drain of the LO buffer is brought out to pin 10 where it is fed DC bias via an inductor. The inductor resonates with the internal and external parasitic capacitance associated with that pin. For maximum performance the resonance must be at or near the 2. Determine the LNA Matching Network Matching network design for the TQ5635 LNA is much simpler than designing with discrete transistors. The TQ5635 LNA was designed so that the optimum noise match is very close to the conjugate match. Thus once a match to 50ohms is attained, only a slight adjustment to the L and C values may be needed for optimum noise figure. If the design uses 5-8mil dielectric FR4 board, then it is likely that the desired LO frequency. Figure 10 shows a properly tuned LO buffer. Notice that the LO frequency range of interest is to the left of the peak. We recommend that the LO is tuned slightly higher in frequency, so that the desired band is on the lower, more gradual side of the slope. Thus there is less change in performance versus frequency. We have also found empirically that tuning the LO slightly higher in frequency results in much better LO input and RF input matches. component values on the evaluation board can be used for a starting point. Alternately, a network can be synthesized from the S-parameter values at the end of this note.
V DD
GND
LNA Out
GND
GND
GND
MXR In GND VDD IF Bias
LNA Out
GND
GND
RF In
GND
TQ5635
RF In
GND
TQ5635
V DD MXR In GND VDD IF Bias LO In
IF Out
GND
For Lower Gain: add a small inductance to pins 15 and 16
Recommended: Ground pins 15 and 16 for maximum gain
Figure 9: LNA Source Inductor Realization
16
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GND
IF Out
LNA Bias VDD
LO In
LNA Bias VDD
TQ5635 Data Sheet
Figure 10: Suggested LO Tuning Response
A first approximation to the needed inductor can be found by the following equation: 1 L = ---------------- - 1nH C (2*pi*F)2 It is likely that when the design is prototyped, the needed inductance will fall between two standard inductor values. It is advised to use a slightly larger inductor and then use the bypass capacitor for fine tuning. When using this method it is important to isolate the tuning inductor/bypass cap node from the Vdd bus, since loading on the bus can affect tuning. A resistor of 3.3ohm to 20ohm has been found to work well for this purpose (R2). where C=1.5pF
Figure 11 shows the recommended test setup for tuning the TQ5635 LO buffer. A network analyzer is set to the center of the LO band +/- 300Mhz, with an output power of -4dBm. It is important to set the frequency range to be quite a bit wider than the LO band, so that the shape of the tuning curve can be seen. A two port calibration is performed and the analyzer is set to monitor S21. Port 1 of the analyzer is connected to the LO port of the TQ5635, while Port 2 is connected via cable to a short length of semi- rigid coaxial probe. The center of the probe should protrude 1 to 2 mm beyond the ground shield. The end of the probe with the exposed center conductor is held close to the LO tuning inductor.
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17
TQ5635 Data Sheet
since there is always some package and bond wire
GND LNA Out GND V DD
COAXIAL PROBE
VDD
inductance back to the die. Furthermore, although some additional IP3 performance may be gained by increasing the quiescent current, in practice it makes no sense to increase Idd beyond that which provides maximum input intercept. At some point IP3 is limited by the mixer FET, and no further increase in input intercept can be obtained by adjusting the IF stage. There are two GIC schemes that are recommended for the
GND
MXR In GND VDD IF Bias
RF In
GND
TQ5635
GND
V DD
IF Out
LNA Bias
LO In
LO IN
PORT 1
MEASURE S21
TQ5635 (Figure 12). The first uses a small resistor (1.0 to 5 ohms) in series with a bypass capacitor to set the AC gain. The IF stage current is then set by the larger resistor (40 to 80 ohms) that connects directly from the GIC pin to ground. The small degeneration resistor lowers the IF stage gain.
NETWORK ANALYZER
Figure 11: LO Tuning Test Setup
The second scheme, which is recommended for maximum gain, uses a resistor in parallel with capacitor. The resistor sets the DC current, while the capacitor bypasses it at the IF frequency. For highest gain, place the capacitor as close to Pin 7 as possible. Try to avoid capacitors which are selfresonant at the IF frequency. Here is an approximate equation for Rgic as a function of IF stage Idd: Rgic ~ 0.6 / IDD_IF
4. GIC Network Design The GIC pin on the TQ5635 is connected internally to the source of the IF output stage. By adding one or two resistors and a capacitor to this pin, it is possible to vary both the IF stage AC gain, and the IF stage quiescent current. However, there is a limit to the amo unt of gain increase that is possible,
GIC PIN
Chip GND
GIC PIN
Chip GND
0 to 5 ohms AC degen 40 to 80 ohms sets IF current Zc bypass at IF Freq 40 to 80 ohms sets IF current
Zc bypass at IF Freq
Figure 12: GIC Pin Networks
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TQ5635 Data Sheet
circuit topology must contain either a RF choke or shunt
dB 12 11 10 9 8 10 7 6 47 56 68 82 100 8 110 12
5635 Mixer NF, Gain, IIP3 and Idd vs GIC resistor
Idd (mA) 16
NF Gain IIP3 Idd
inductor. For purposes of 50 ohm evaluation, the shunt L, series C, shunt C circuit shown in Figure 14 is the simplest and requires the fewest components. DC current can be easily injected through the shunt inductor and the series C provides a DC block, if needed. The shunt C, in particular can be used to improve the return loss and to reduce the LO leakage. The circuit is used on our evaluation board. For matching into a filter, the circuit of Figure 15 works well. The network provides the needed impedance transformation with a lower loaded Q using reasonable inductor values. Thus matching circuit loss is minimized. The ratio between (L1+L2) and L2 is proportional to the square root of the impedances to be matched, Z1 and Z2. The sum of L1 and L2 must be chosen so that the total inductance resonates with the SAW input capacitance. If this resonant frequency is
14
GIC resistor (kOhms)
Figure 13: Mixer Performance as a Function of Rgic
5. IF Match Design The Mixer IF output (Pin 7) is an "open-drain" configuration, allowing for flexibility in efficient matching to various filter types and at various IF frequencies. An optimum lumpedelement-matching network must be designed for maximum TQ5635 conversion gain and minimum matching network loss. When designing the IF output matching circuit, one has to consider the output impedance, which will vary somewhat depending on the quiescent current and the LO drive. The IF frequency can be tuned from 45 to 400 MHz by varying component values of the IF output matching circuit. The IF output pin also provides the DC bias for the output FET. In the user's application, the IF output is most commonly connected to a narrow band SAW or crystal filter with impedance from 500 -1000? with 1 - 2 pF of capacitance. A conjugate match to a higher filter impedance is generally less sensitive than matching to 50? . When verifying or adjusting the matching circuit on the prototype circuit board, the LO drive should be injected at the nominal power level (-4 dBm), since the LO level does have an impact on the IF port impedance. There are several networks that can be used to properly match the IF port to the SAW or crystal IF filter. The IF FET bias is applied through the IF output Pin 7, so the matching
much higher than the IF frequency, then Copt can be added to lower it. Please note that because of parasitic capacitance and the discrete values of commercial inductors, the formulas of Figure 15 only serve as a starting point for experimentation. In order to minimize loss, any inductors used should have high Q. Typically 0805 size inductors perform better than the 0603 size. If 0603 inductors must be used for space considerations, make certain to use High-Q types. It is possible to introduce 3dB of additional loss by using low Q inductors. Additionally, it is recommended to place the IF filter very close to the TQ5635. If the two are far apart a transmission line will be needed between them. In that case two matching networks will be needed, one to match down to 50ohms and one to match back up to 1000ohms. Twice the loss can be expected for such a scheme.
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TQ5635 Data Sheet
Vdd
6. Mixer RF Input Matching Network: Although the TQ5635 can present <2:1 SWR to the SAW filter without a matching circuit, it is still recommended to use an inter-stage network. We have found that the Mixer-Filter interaction discussed earlier can result in degraded OIP3 at higher LO power levels with no network. Probably more time
bypass
L Cseries IF OUT
50 will be needed for this phase of the design than for any other, ohms since it involves a process of trial- and-error.
For example, the evaluation board network was chosen after
Cshunt
trying all three of the types of Figure 16. For each type, there was found component L and C values which gave >10dB return loss at the RF frequency (LO is turned on for this testing). Then a SAW filter was added in cascade and IP3 was tested. The circuit of Figure 12-C was found to have superior IP3. The final test of the filter-network-mixer cascade is to connect a network analyzer at the SAW input and measure S11 with the mixer turned on. A 2:1 or better SWR should be seen in the RF pass band of the SAW. At that point, the filternetwork-cascade is ready to be tested with the LNA.
Figure 14: IF Output Match to 50 ohms
Vdd
bypass
RF In
14 2 12
L2 IF OUT Z1
TQ5635 Mixer
A
Z2
SAW
L1 Csaw Copt
IF SAW
balanced IF Out
TQ5635 LNA
RF In 2
14 12
TQ5635 Mixer
B
SAW
L1 ? L 2
Z2 ? L2 Z1
1 ? CSAW 4? FIF (L1 ? L 2)
2 2
TQ5635 LNA
Z2
RF In 2
14 12
TQ5635 Mixer
C
L1 Z1 Csaw L2
SAW
Equivalent Circuit
TQ5635 LNA
Figure 16: SAW -Mixer Input Networks
Figure 15: IF Match to a SAW Filter
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TQ5635 Data Sheet
7. Redo GIC Components: After obtaining the optimum network between the SAW and Mixer RF input, most likely Idd will have changed slightly. Determine a new GIC resistor to bring Idd to the desired value. 9. Test the TQ5635 Cascade: Finally after the LNA and Mixer are properly tuned the device performance as a whole should be measured. 8. Double Check IF Match A match to a 1000ohm filter will not be as sensitive. The LO must be turned ON during the test.
After any change which affects IF stage current it is importa nt to recheck the IF output match. This is especially true when matching down to 50ohms, since the match is more sensitive.
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TQ5635 Data Sheet
Package Pinout:
GND/LNA Gain GND/LNA Gain LNA Out Mixer Vdd
1 GND
Active Bias MXR In
RF In
LNA
GND
Mixer GND LO Vdd
LNA Bias
active bias
LO Buffer IF Amp
LO In
LNA Vdd
GND
IF Out
GIC
Pin Descriptions:
Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15, 16 Paddle Pin Name GND LNA IN GND LNA BIAS LNA VDD GND IF OUT IF BIAS LO IN LO TUNE GND MXR IN MXR Vdd LNA OUT LNA SOURCE GND Description and Usage Ground connection. Connect as closely as possible to ground or to package paddle ground. LNA RF input (DC blocked internally). An external match is required which can be chosen for a gain/NF trade-off. Ground connection. Connect as closely as possible to ground or to package paddle ground. An external resistor is connected between this pin and Vdd in order to set the LNA bias current. A value of ~ 2.5 KOhm will give an LNA IDD of ~ 7 mA. LNA supply voltage. An external decoupling/bypass network should be used. Ground connection. Connect as closely as possible to ground or to package paddle ground. Mixer IF output (~ 500 Ohm, open drain). Connection to Vdd required. External matching required. IF amp FET source. An RF by -passed resistor is placed form this pin to ground in order to set the current in this stage. Mixer LO input (DC blocked internally). Internally matched to ~ 50 Ohms. Mixer LO buffer supply voltage. An external bypass capacitor required. An external series inductor is required for peaking LO gain. Ground connection. Connect as closely as possible to ground or to package paddle ground. Mixer RF input (DC blocked internally). An external matching network is recommended to optimized cascaded IIP3 Supply voltage for the internal bias circuit that sets IF amp current (in conjunction with the external IF BIAS resistor). LNA RF output. It is DC blocked and internally matched to better than 2:1. The source node of the cascade LNA section. A hard ground provides maximum gain and minimum IIP3. A small amount of external inductance will reduce gain and improve IIP3. Ground connection. It is very important to place multiple via holes under the paddle. Provides RF grounding for the part.
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TQ5635 Data Sheet
Recommended PC board Layout to Accept 16 Pin Lead-less Plastic Package:
1.10 [0.043]
0.13 [0.005]
0.25 [0.010] 0.55 [0.022]
A
1.10 [0.043] 0.50 [0.020] PITCH 4X SIDES
0.53 [0.021]
DETAIL A
1.10 [0.043]
PACKAGE OUTLINE
LEADLESS 3x3-16 PCB FOOTPRINT
NOTES: 1. ONLY GROUND SIGNAL TRACES ARE ALLOWED DIRECTLY UNDER THE PACKAGE. 2. PRIMARY DIMENSIONS ARE IN MILLIMETERS, ALTERNATE DIMENSIONS ARE IN INCHES.
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23
TQ5635 Data Sheet
Package Type: QFN 3x3-16 Lead-less Plastic Package
D
D2
PIN 1 L E E2
PIN 1
LASER MARK PIN 1 ID
e
A
b
JEDEC DESIGNATION A b D D2 e E E2 L
DESCRIPTION OVERALL HEIGHT TERMINAL WIDTH PACKAGE LENGTH EXOPSED PAD LENGTH TERMINAL PITCH PACKAGE WIDTH EXPOSED PAD WIDTH TERMINAL LENGTH
METRIC 0.90 +/-.10 mm .250 +/-.025 mm 3.00 mm BSC 1.80 +/-.15 mm .50 mm BSC 3.00 mm BSC 1.80 +/-.05 mm .40 +/-.05 mm
ENGLISH .035 +/-.004 in .010 +/-.001 in .118 in .071 +/-.006 in .020 in .118 in .071 +/-.002 in .016 +/-.002 in
Notes 1 1 1 1 1 1 1 1
Notes: 1. Primary dimensions are in metric millimeters. The English equivalents are calculated and subject to rounding error.
Additional Information Additional Information
For latest specifications, additional product information, worldwide sales and distribution locations, and information about TriQuint: Web: www.triquint.com Email: info_wireless@tqs.com Tel: (503) 615-9000 Fax: (503) 615-8902
For technical questions and additional information on specific applications: Email: info_wireless@tqs.com
The information provided herein is believed to be reliable; TriQuint assumes no liability for inaccuracies or omissions. TriQuint assumes no responsibility for the use of this information, and all such information shall be entirely at the user's own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. TriQuint does not authorize or warrant any TriQuint product for use in life-support devices and/or systems. Copyright (c) 2001 TriQuint Semiconductor, Inc. All rights reserved. Revision A, February 22, 2001
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TQ5635 Data Sheet
For latest specifications, additional product information, worldwide sales and distribution locations, and information about TriQuint: Web: www.triquint.com Email: info_wireless@tqs.com Tel: (503) 615-9000 Fax: (503) 615-8902
For technical questions and additional information on specific applications: Email: info_wireless@tqs.com
The information provided herein is believed to be reliable; TriQuint assumes no liability for inaccuracies or omissions. TriQuint assumes no responsibility for the use of this information, and all such information shall be entirely at the user's own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. TriQuint does not authorize or warrant any TriQuint product for use in life-support devices and/or systems. Copyright (c) 2001 TriQuint Semiconductor, Inc. All rights reserved.
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