[time-nuts] DMTD using Active Mixers

[Magnus Danielson]

Bruce Griffiths wrote:
> Magnus Danielson wrote:
>> Bruce Griffiths wrote:
>>> Active mixers almost invariably have a higher noise floor than 
>>> passive mixers, particularly in the flicker noise region.
>>> Consequently a DMTD system using active mixers will have a higher 
>>> system noise floor than one using active mixers.
>>
>> ... than one using passive mixers.
>>
>> You still need driving amplifiers.
>>
>> Cheers,
>> Magnus
>>
> Its much easier to ensure that the flicker phase noise of a buffer 
> amplifier is low than it is to achieve a low flicker phase noise for an 
> mixer using nonlinear active devices.
> Even passive FET mixers have higher flicker noise than passive mixers 
> using schottky diodes.

True, but my comment was rather to say that it will most probably not be 
all passive, but I completely agree (as you very well know) that phase 
noise of amplifiers is much better contained than that of mixers.

Cheers,
Magnus