[time-nuts] DMTD - analog multiplier vs. diode mixer ?

Bob Camp kb8tq at n1k.org
Fri Jan 8 17:42:05 EST 2016


Hi

The board I have uses high speed CMOS single gate XOR’s. They have a pretty good
phase noise floor (-170’s) so they should be pretty reasonable. 

Bob

> On Jan 8, 2016, at 12:16 PM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
> 
> 
> 
> On 1/7/2016 3:11 PM, Bob Camp wrote:
>> Hi
>> 
>> If your intention is to run a mixer with saturated inputs …. just run
>> an X-OR gate. It will handle the high level signals much better than
>> an over-driven analog part.
> 
>> Bob
>> 
> 
> If you look at the schematic of an XOR gate IC and compare it
> to the schematic of, for example, an MC1496 mixer, you will
> see a lot of similarity.  If the gate is of the ECL type,
> it will have the addition of emitter followers, but that
> it a minor detail of implementation.  I'm not sure there
> is a huge difference.  ECL is a great logic family in
> general (self-confessed ECL-phile here :-) but it is
> probably the worst for phase noise, compared to the
> saturating logic types.
> 
> Rick Karlquist N6RK
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