Hi Bigboss,
Thank you for your input. With a channel spacing of 100kHz, Loop bandwidth say is 10kHz. This means that the settling time taking approx. 10/LB = almost 1ms. This is a little too much time for the application.
I am wondering if there are things that can be done to speed up the lock time - eg. perhaps use a mixed mode with also frac N mode of operation to get to the settling time quickly.
I also want to get a sense of what others have been able to do - on this board, someone posted saying they could get settling times to under 200us for 200kHz channel spacing. If there are any relevant references or other publications, I would like to get these.