TA0030 Datasheet, PDF (5/6 Pages) RF Micro Devices – TRANSMIT AND RECEIVE AGC AMPLIFIERS FOR CDMA CELLULAR /PCS PHONES

TA0030
Measurement
Reference Plane
Z_S=500 Ω
Z _{S, EFF}=333 Ω
CDMA IF Filter
CDMA+
1
R1:
CDMA-
1 kΩ
2
Z _{IN, EFF}=500 Ω
Z _IN=1 kΩ
FM IF Filter
3
Z _IN=850 Ω
FM IN
4
IN
SEL.
Z_S=850 Ω
10 nF
5
6
IF IN
SELECT
7
NC 8
GAIN
CONTROL ^{1 6}
15
14
13
12
11
10
9
Z_LOAD,EFF=250 Ω
R1 sets the CDMA balanced input impedance. The effective input
impedance is then 500 Ω.
R2 sets the balanced output impedance to 500 Ω. L1 and C2 serve dual
purposes. L1 serves as an output bias choke, and C2 serves as a series DC
block. In addition, the values of L1 and C2 may be chosen to form an
impedance matching network of the load impedance is not 500 Ω.
Otherwise, the values of L1 and C1 are chosen to form a parallel-resonant
tank circuit at the IF when the load impedance is 500 Ω.
Figure 8. RF2607 Application Circuit
system designer only wishes to use the modulator/
AGC section. In the receive chain, a demodulator is
added to the receive AGC amplifier. In this case, the
output of the part is I/Q data at baseband frequencies.
4.7 kΩ
GC
10 nF
10 nF
V_CC
C1 L1
C2
R2:
500Ω
C2
Z_LOAD=500Ω
OUT+
OUT-
C1 L1
V_CC
Measurement
Reference Plane
10 nF
Z_OUT=500 Ω
The RF9957 CDMA Receive IC includes both of these
functions. Both the RF9957 and RF9958 operate from
a single 3V power supply.
  
The RF2607 and the RF2609 are two critical compo
nents of the RF section of a CDMA phone (see Figure
9). Both of these IC's were designed to meet all of IS-
95's worst-case requirements and are available in high
volume at low cost. Please call RF Micro Devices' Mar-
keting Department for additional information and
details on these two products, or any others, at 910-
664-1233. Also, please check our web page at
www.rfmd.com.
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Copyright 1997-2000 RF Micro Devices, Inc.
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