RF2607
Application Schematic
10
Measurement
Reference Plane
ZS=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.
ZS=850 Ω
10 nF
5
6
IF IN
SELECT
7
NC 8
GAIN
CONTROL 16
15
14
13
12
11
10
9
ZLOAD,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.
4.7 kΩ
GC
10 nF
10 nF
VCC
C1 L1
C2
R2:
500Ω
C2
ZLOAD=500Ω
OUT+
OUT-
C1 L1
VCC
Measurement
Reference Plane
10 nF
ZOUT=500 Ω
10-4
Rev B2 010720