Hi Bruce... Thanks for your answer...
I have a couple of questions: 1. I am using a 1kHz beat frequency, and measure back2back period using a Pendulum CNT-91 high resolution frequency counter. Does the DC stability of the mixer still matter? 2. I have been comparing the AD831 with some passive mixer, but i can not see any great improvement. I am basically following this procedure: a. As I just want to compare the mixers, using only one of them I mix 10MHz from a Rb with 10MHz+1kHz generated by a R&S signal generator referenced to the same Rb. For passive mixer, I amplify before the mixer, I have also tested different input levels at both LO and RF signal. b. Filter the high component. c. ZCD - Hard limitter, using Collins-type amp. d. Calculate ADEV at 1s. Any approach on how to test the mixer? My goal is to reach an accuracy of 5E-14 @ 1s Regards, Mario On Thu, Nov 12, 2009 at 10:35 AM, Bruce Griffiths < [email protected]> wrote: > Mario > > No there is no diode mixer in the AD831, it uses a conventional Gilbert > cell mixer with preceding LO and RF amplifiers. > Compared to a diode mixer it has high flicker noise and poor dc stability. > > Bruce > > > Mario Sanchez wrote: > >> Thanks for your inputs... >> >> I dont know exactly which are the microcircuits ActiveMixers you refer to; >> just to make it clear, the IC that I am using is Analog Devices AD831, >> which >> basically has a conventional diode mixer, a limiter amplifier in the LO >> input and a low noise output amplifier. >> >> Regards, >> Mario >> >> >> On Thu, Nov 12, 2009 at 1:39 AM, Magnus Danielson< >> [email protected]> wrote: >> >> >> >>> Bruce Griffiths wrote: >>> >>> >>> >>>> Hej Magnus >>>> >>>> To confuse matters Minicircuits use the term active mixer for a >>>> conventional diode mixer that uses amplifiers on the LO and/or RF ports >>>> to >>>> boost signal levels. >>>> >>>> >>>> >>> While it confuses matters, it is usefull to know about them, since they >>> may >>> be good for some designs, but maybe not for DMTD designs. >>> >>> I have argued that keeping a buffer-amplifiers (not to be confused with >>> the >>> -120 dB isolational amp) just at the mixer will relief the issues of VSWR >>> to >>> tempco. Also, getting that extra boost is also good. Needs to have >>> meaningfull phasenoise to be usefull thought. >>> >>> >>> Whereas I was referring to mixers like gilbert cell mixers as active >>> >>> >>>> mixers. >>>> >>>> >>>> >>> I was making the same distinction. Passive JFET mixers is just another >>> variant to using schottkydiodes. >>> >>> >>> With the Minicircuits so called active mixers one needs to measure their >>> >>> >>>> phase noise in order to make meaningful comparisons. >>>> >>>> >>>> >>> Indeed. Their target is probably not considering cutting edge DMTD >>> systems. >>> >>> Cheers, >>> Magnus >>> >>> >>> _______________________________________________ >>> 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.
