TETRA Baseband Processor
FX980
1.4
External Components
Rx Inputs
When using the internal anti-alias filter, the following is suggested
R2
R2
C2
R1
IRXP
R1
AGC
R1
QRXP
C2
R1
C1
QRXN
C1
IRXN
Filter 1
R2
R2
Example values:
R1 = 220
Ω
R2 = 408
Ω
C1 = 1.5nF (R1, C1 precise values are not critical) (-3dB at 240kHz)
C2 = 3.9nF (R2 x C2 time constant should be preserved) (-3dB at 50kHz)
When not using the internal anti alias filter, it is suggested that the user should follow the guidelines in Section
1.5.3.1. In both cases, there should be at least one filter pole close to the chip inputs.
Figure 2a Recommended External Components - Rx Inputs
Tx Outputs
R3
ITXP
C3
R3
ITXN
R3
QTXP
R3
QTXN
C3
C3
C3
Example values:
R3 = 220
Ω
C3 =
1nF
Decoupling capacitors should be employed as detailed in Section 1.5.1
Figure 2b Recommended External Components - Tx Outputs
©
1997
Consumer Microcircuits Limited
6
D/980/3
CMLMICRO [ CML MICROCIRCUITS ]
