[time-nuts] DMTD Mixer Terminations

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Mar 4 21:45:25 UTC 2010


The specifications for the maximum output given on the datasheet are so 
wide that the 20% higher than typical beat frequency amplitude may well 
be within spec.
The RPD-1's were being over driven by about 2.5dBm or so, which would 
also tend to increase the output.

A test made with 500 ohms to ground as shown in a Minicircuits 
application note had about the same output as when terminating the IF 
port in 50 ohms + 47nF.

The remaining questions are:
1)What effect does the IF port termination have on the phase detector 
phase noise spectrum?

2) What effect does the IF port termination have on the noise to phase 
detector gain ratio?

Bruce

Joseph M Gwinn wrote:
> time-nuts-bounces at febo.com wrote on 03/03/2010 10:56:46 PM:
>
>    
>> From:
>>
>> Bruce Griffiths<bruce.griffiths at xtra.co.nz>
>>
>> To:
>>
>> Discussion of precise time and frequency measurement
>>      
> <time-nuts at febo.com>
>    
>> Date:
>>
>> 03/03/2010 11:03 PM
>>
>> Subject:
>>
>> Re: [time-nuts] DMTD Mixer Terminations
>>
>> Sent by:
>>
>> time-nuts-bounces at febo.com
>>
>> Whilst your corrected measurements for the 10534 and 10514 are now
>> within about 10% of those found by NIST for one of their mixers, the
>> discrepancy with Minicircuits estimates for the RPD-1s is somewhat
>> larger but their phase detector gain specs seem incompatible with their
>> max output specs.
>>      
> The diode ring mixers MiniCircuits offers as phase detectors are usually
> designed for and characterized at 500 ohms load, not 50 ohms.  Does this
> resolve the discrepancy?
>
> Joe
>
>
>
>
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