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10-4
RF2607
Rev B2 010720
10
Application Schematic
1
2
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7
8
16
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10
9
NC
GAIN
CONTROL
IN
SEL.
10 nF
R1:
1k
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
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