On Tue, 31 Dec 2019 12:00:02 -0500, [email protected] wrote: Re: time-nuts Digest, Vol 185, Issue 39
> ------------------------------ > > Message: 7 > Date: Tue, 31 Dec 2019 11:01:10 -0500 > From: Dan Kemppainen <[email protected]> > To: [email protected] > Subject: [time-nuts] PLL suggestions > Message-ID: <[email protected]> > Content-Type: text/plain; charset=utf-8; format=flowed > > Hi All, > > We've got a project going on where we need a 125MHz clock that should be > locked to 10MHz. I'm considering an on board 10MHz oscillator and > external 10MHz input to utilize an external standard to lock the 125MHz > which would PLL a 125MHz source. > > The 125MHz becomes a reference for 3.125Ghz, as well as logic running at > 125Mhz. (Currently this system is running on small 125MHz TCXO.) > Basically we need a reasonably clean 125MHz signal, but locked to 10Mhz > for frequency reference. > > We've identified a few VCXO's that seem to be low noise and are small > enough. The 10Mhz is easy enough. However my stumbling block is a simple > PLL. > > What I'm looking for is a simple, small PLL chip. Something with > external analog loop filter components to allow easy tweaking would be > preferred. > > In my perfect world, this chip would be a COTS part, with pin strappable > divider configuration or similarly simple hardware configuration. An OTP > device would work as well, as would one with it's own memory and > external programmer. If necessary a small PIC or similar could be used > to configure the PLL, but that's one chip which would be nice to avoid. > > Smaller compact package SMT parts are fine. This is going on a board > with lots of SMT components, leadless flat pack devices and BGA's, so > smaller is better. > > If any of you have any suggestions, I'd appreciate it. > > Happy new year! > Dan > This sounds like an Ethernet over fiber application. If so, the phase-noise requirements are not all that stringent, and there are many COTS components available. If I recall, Texas Instruments makes a "clock cleaner" IC that can be used here. Joe Gwinn _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
