[time-nuts] Minicircuits SYPD-1

[Bob kb8tq]

Hi

There have been several threads on the SYPD-1 and it’s cousin in a different package the RPD-1. Both are designed targeted 
as phase detectors rather than mixers. While you can never say “always” the best performance generally is to drive both 
RF ports hard from matched sources. Terminate the IF port in a high impedance (> 5K ohms) and run a low noise op amp after
it. My preference is to run a positive gain amp. As others will caution - this risks blowing the amp in the case of a power supply
failure. I’m careful with power supplies ( = have not blown one out that way in 30 years). 

With something like a gain of 10 in the op amp stage, you will almost clip / will clip the output running unlocked. Obviously if it 
clips, drop the gain or increase the supply voltage. The open loop part lets you calibrate the phase slope of the detector. You 
need that to evaluate the data you get. 

For phase noise, you normally run a single mixer in phase quadrature. Easy way to do this is to feed DC out of the op amp into
the control port on one of your sources. You likely will need gain / attenuation in this path as well as an offset voltage. 

Once in quadrature, you feed the output of the op amp into a sound card or spectrum analyzer. The noise you read out is (after 
a bit of math based on the calibration) the phase noise of the sources. You can get well into the  160’s (and maybe further) 
with a setup like this. 

Bob 

> On Dec 19, 2018, at 2:18 AM, jerry <jerry at hanler.com> wrote:
> 
> 
> Hello,  
> I'm playing around with various methods of collecting data for oscillator testing and would like to try the loose PLL which requires a phase detector (PD).  I'm testing an AD8302 but that has a flat spot around 176 to 180 degrees.  One of the papers I read recommended the subject PD but it is out of stock everywhere, including the subs. One Minicircuits PD is in stock but pricey.  I can try a double balanced mixer like the SBL or TUF series (which I have on hand) but I thought maybe someone on the list has the subject PD they dont need.   If so, please send me a note.
> I'm slowly gathering parts for Riley's small Dual Mixer Time Difference test kit but it will take some time which I'm unfortunately running out of due to mild Parkinsons getting in the way of SMD soldering. I've used my HP 5371a in the past but it sounds like a jet engine.  I recently ordered a TICC as well.  By the time I'm done I probably will have purchased more than a commercial  product, ha!
> Jerry
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