TQ5132 데이터 시트보기 (PDF) - TriQuint Semiconductor
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TQ5132 Datasheet PDF : 12 Pages
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TQ5132
Data Sheet
CDMA IF Amplifier
The CDMA IF amplifier is an open drain stage with a gain step
to adjust the output power levels according to the system
requirement. No quiescent current adjustments are possible in
this mode since the self-bias circuit is on-chip. While the IF
output can be tuned for frequencies as high as 500 MHz, the
downconverter performance is limited by the internal tuned
circuit of the LO buffer amplifier. The highest IF that can be used
without significant deviation from typical performance is 130
MHz. This output is a high impedance open drain FET z = 5.47
– j 0.71 Ω (normalized). The match requires a RF choke to Vdd
for proper biasing (see figure 3). Typical CDMA IF output
impedance is shown in figure 4. The gain of the CDMA IF
amplifier can be adjusted according to the degeneration resistor
value R2 (see figure 5).
TQ5132
CDMA
IF
Output
1
8
2
7
3
6
C6=27pF
4
5
C7=30pF
L2=180nH
Vdd
Note: These values were optimized for TriQuint's 5131 Demo
board. The discrepancy between these values and those of the
customer's application may differ due to board and component
parasitics.
Figure 3. TQ5132 CDMA IF Output Match (IF = 85MHz)
0.5
0.5
1.0
2.0
1.0
2.0
B
TQ5132
CDIF output
B Impedance
0.70 @ -2.8
z = 5.47- j 0.71
y = 0.18 + j 0.02
Freq=85MHz
-0.5
-2.0
-1.0
Figure 4. TQ5132 CDMA IF Output Impedance at Pin 4
AMPS IF Amplifier
The source of the AMPS IF amplifier is connected directly to pin
3. This allows the system designer to adjust Gain, output
Intercept and Current (GIC) by adding an external self-bias
circuit at this pin (see figure 5). A large bypass capacitor value
in the self-bias circuit minimizes the effects of low frequency
components present at this pin. TriQuint recommends 0.022uF
or greater. The AMPS IF amplifier gain is only mildly affected by
the value of R2.
TQ5132
1
8
2
7
R2
3
6
R3
C4 4
5
C4 = 0.022uF
R2 = 6.8 Ω
R3 = 180 Ω
Note: These values were optimized for TriQuint's 5131 Demo
board. The discrepancy between these values and those of the
customer's application may differ due to board and component
parasitics.
Figure 5. TQ5132 AMPS GIC pin
Once the operating point is chosen, the designer still has
flexibility to adjust gain and intercept by varying the ratio of the
DC bias resistors, R2/R3. Maximum gain is obtained when the
total DC resistance (R2 + R3) at pin 3 is bypassed.
The normalized impedance of the AMPS IF output is z = 15.4 – j
2.87 Ω. This particular measurement was taken on the 5132
demo board by lifting pin 5 of the PCB pad and soldering the
center conductor of a semirigid probe next to it. The outer
conductor was grounded close to the pin and its electrical length
dialed as a port extension in order to move the calibration
reference plane right at the tip of the probe. Keep in mind that
the total DC bias resistance in the GIC pin must be selected
before taking this measurement. When designing the PCB, it is
recommended to place the self-bias circuit of the amplifier as
close to the pin as possible to minimize possible loading effects
that might cause oscillation. Similarly, the shunt capacitor C10
8
For additional information and latest specifications, see our website: www.triquint.com
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