13-155
TA0030
13
Copyright 1997-2000 RF Micro Devices, Inc.
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.
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.
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
GAIN
CONTROL
IN
SEL.
10 nF
R1:
1 k
Ω
CDMA-
FM IN
CDMA+
IF IN
SELECT
4.7 k
Ω
GC
10 nF
L1
L1
V
CC
C2
OUT+
OUT-
V
CC
R2:
500
Ω
C1
C1
C2
Measurement
Reference Plane
Z
LOAD=500Ω
FM IF Filter
CDMA IF Filter
Z
S=500 Ω
Z
IN, EFF=500 Ω
Z
IN=1 kΩ
Z
S=850 Ω
Z
S, EFF=333 Ω
Z
IN=850 Ω
Measurement
Reference Plane
Z
LOAD,EFF=250 Ω
Z
OUT=500 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.
10 nF
10 nF
Figure 8. RF2607 Application Circuit
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