[time-nuts] Best phase detector / mixer for 100MHz?

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Nov 24 05:34:03 UTC 2012


Magnus Danielson wrote:
> Hi Anders,
>
> On 11/23/2012 04:42 PM, Anders Time wrote:
>> I have been using an minicircuits mixer as a phase detector for 
>> measuring
>> low frequency(5-10MHz) and it is usually good enough. But when I want to
>> measure 100MHz the sensitivity of the mixer decreases a lot, so when 
>> I want
>> to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm
>> out) oscillators the sensitivity is not good enough. I read in an old
>> article by Walls, Stein et al(Design considerations in state-of-the-art
>> signal processing and phase noise measurement system) that one can 
>> use two
>> diodes in series in the double balanced mixer to increase the 
>> sensitivity.
>> I tried this with some standard 1n5711 Schottky and the sensitivity 
>> is now
>> 1V/rad, but is there a easier way to do this? /Anders
>
> Craig Nelson and friends over at NIST had a little different stab at 
> mixer which might interest you:
> http://tf.boulder.nist.gov/general/pdf/2554.pdf
>
> This was intended for 5 MHz, but I am sure you would enjoy reading 
> about it never the less.
>
> Cheers,
> Magnus
>
They've subsequently used it at 10MHz, 20MHz and 40MHz in regenerative 
dividers.

Bruce




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