[time-nuts] DMTD using Active Mixers

[Mario Sanchez]

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 <
magnus at rubidium.dyndns.org> 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
>
>
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