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