Hi Paul. PLL's of course can introduce phase-noise, as well as remove it. Certainly if the reference 5 MHz is (phase)noisy then a PLL can clean that up, but if you multiply it (before cleaning) it gets much worse.   The multipliers themselves as someone else may chime in, can add to that I suspect too. I missed your original question, so did not realise you wanted to multiply up that far. Do you subscribe to Dubus?  There's a description of a 122 GHz system in the current issue, using (from what I can gather) IC's used for collision avoidance/adaptive-cruise control etc, in modern vehicles..   PL locked (sort-of) to a GPS PPS source too, phase noisy at 122 GHz, but good enough for FM voice it seems! http://www.marsport.org.uk/dubus/last.htm   (Just the front cover.) There is a sample full issue at  https://www.dropbox.com/s/6gusksmazh7wmyy/DUBUS412w.pdf?dl=0  (that describes a 134 GHz transverter)  If you've not come across that publication before. 73 Paul. Dave G0WBX ------------------------------------------------------------------------ > Subject: Re: [time-nuts] 5 Mhz to 10 Mhz and 25 Mhz > Message-ID: <B66D51BC70084A0E8B4F9F5BCDB4C373@precision380> > Content-Type: text/plain; charset="iso-8859-1" > > Hi Dave I posted the question as I am not up to speed with the latest > solutions > But I want the lowest phase noise that is easily possible so you might be > correct as it is to lock up a 10 Ghz receiver but later for a 120 Ghz > receiver > > Regards Paul -- Created on and sent from a Unix like PC running and using free and open source software: