Ah, now I get the basic idea. I'll need to think about it for a while. Many thanks for the links. Chris Stake
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bruce Griffiths Sent: 30 June 2010 09:08 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] yet another GPSDO design, or so Here's a link to a pdf version of the synchronously filtered low ripple pwm dac: http://www.edn.com/contents/images/6553625.pdf Bruce Bruce Griffiths wrote: > Chris > > All the details are in the article: > http://www.edn.com/contents/images/6607197.pdf > > However it would be best to read the article posted by Bob Camp first: > > > Bruce > > Chris Stake wrote: >> Hi Bruce, >> This sounds like a promising idea, please could you expand on the >> synchronous filter technique? I have seen some articles about how such >> filters can be used to "clean up" the data from rotating machinery for >> vibration analysis etc. but I don't follow how they can be used in a PWM >> application. >> Regards >> Chris Stake >> >> >> >> Its possible to build a 24 bit resolution D/A using a synchronously >> filtered PWM circuit. >> A pair of PWM outputs and a few relatively low precision resistors and >> capacitors together with a low noise low drift reference are required. >> The technique takes advantage of the fact that the required EFC voltage >> changes slowly and isnt updated at a highg rate. >> The synchronous filter technique eliminates the very long time constant >> RC filters required with an asynchronously filtered PWM waveform. >> >> Bruce >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
