[time-nuts] DMTD using Active Mixers
magnus at rubidium.dyndns.org
Thu Nov 12 00:39:02 UTC 2009
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
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.
More information about the time-nuts