Further to my previous post: I note that the LTC6957 is 3.3V CMOS rather than 5V. Do you have a recommmendation for a level converter to 5V logic? Would a 74AC04 using a 5V supply cope well enough in that role or is there a better solution?
Regards, David Partridge -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of br...@ko4bb.com Sent: 29 July 2014 12:00 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Sine to square wave converter Phase Noise Sorry, I meant the LTC6957-4 of course._SELA = l FILTA = L FILTB = H ie an input stage BW of 160MHz as recommended for a 10MHz + 10dBm input. Input for the HX4210 was +14dBm. Comparator was that used in David Partridge's programmable divider (includes the 74AC04 buffers). Bruce > On July 29, 2014 at 5:37 AM Magnus Danielson > <mag...@rubidium.dyndns.org> > wrote: > > > You alternate LTC7957-4 and LTC6957-4 and it is only the later that exists. > > The LTC6957-4 has a single-stage amplifier stage input, with somewhat > programmable bandwidth. I assume you used the 50 MHz BW setting. > > Cheers, > Magnus > > On 07/29/2014 10:55 AM, br...@ko4bb.com wrote: > > Recently I have been comparing the phase noise of the HOlzworth > > HX4210 and the LTC7957-4. > > I have found that the performance of these devices is comparable > > with a 10MHz sinewave input with a PN noise floor below -160dBc/Hz. > > For offsets below 100Hz the LTC6957-4 is quieter and for offsets > > below 50Hz or so is lower than that of my measurement setup. > > I merely mounted the LTC evaluation board in a diecast metal box to > > reduce the effect of air currents on the LTC7957-4 and used an ultra > > low noise 3.3V power supply (Abracon) to minimise the power supply > > contribution to the measured phase noise. > > Achieving a phase noise performance equal to that on the datasheet > > was relatively easy. > > In fact for low offsets the phase noise is lower than that shown on > > the datasheet. > > > > I've also measured the phase noise of a comparator based sine to > > CMOS converter and its PN floor is about 20dB higher than that of > > the LTC6957. > > On completion of measurements PN plots for the various sine to > > square conveters tested will be added to the web pages I maintain on > > Didiers site.. > > > > > > Bruce > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.