EV9900A Datasheet, PDF (23/27 Pages) CML Microcircuits – Test Access for Important Signals

Evaluation Kit for CMX990
EV9900A
6.7.2 Transmitter Operation
Error Observed
Transmitter loop does not lock
Transmitter loop does not lock
Poor modulation spectrum in
transmit.
Possible Cause
No modulation is present.
The PA is not turned on.
An incorrect filter has
been chosen for the
selected Tx IF.
Remedy
Ensure the transmitter is
outputting data. The TSO
command can be used to
continuously send data for
testing. Note also the modem
needs to be in transmit mode
and main DAC enable (register
$03)
Check the feedback coupling
level to the CMX990. Ensure the
correct coupler for the band of
interest is selected.
Select the correct filter using
bits 5 and 6 of the Aux PLL M
div MSB register ($26).
© 2007 CML Microsystems Plc
23
UM9900A/3