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
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