If this is for noise (i.e. jitter) filtering, then I think you want one with
an external loop filter, so you can control the loop bandwidth to your
particular needs, depending on the relative jitter of your input source and
the VCO. Many modern clock PLLs have internal loop filters that don't let
you do this.
**** To unsubscribe from si-list: send e-mail to email@example.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****