CMX989 Datasheet, PDF (6/31 Pages) CML Microcircuits – CDPD MAC and Data Pump Processor

CDPD MAC and Data Pump Processor
1.4 External Components
CMX989
Typical Values:
R1 1MΩ
± 5%
C1 0.1µF
R2 Note 1
± 10%
C2 33pF
R3 100kΩ
± 10%
C3 33pF
R4 100kΩ
± 10%
C4 0.1µF
X1 4.9152 MHz (ref.
section 1.7.1)
)
)
) ± 20%
)
C5 100pF
C6 6.8nF
C7 6.8nF
C8 0.1µF
)
)
) ± 20%
)
Notes:
1. R2, R3, C4 and C5 form the gain components for the Rx INPUT.
R2 should be chosen as required by the signal input level, using the following formula:
Gain = -R3/R2
2. Connections labelled ‘N/C’: No internal connection, do not use.
Figure 2 Recommended External Components
To achieve good noise performance it is very important to decouple V_DD and V_BIAS and to protect the
receive path from extraneous in-band signals. It is recommended that the printed circuit board is laid out
with a ground plane in the CMX989 area to provide a low impedance connection between the V_SS pin and
the V_DD and V_BIAS decoupling capacitors. It is also important to provide a low impedance connection
between the Xtal capacitors (C1 and C2) and the ground plane.
© 2001 Consumer Microcircuits Limited
6
D/989/2