AD8302 Full phase detection

Q 

I have purchased an AD8302 evaluation board and am looking to use it to detect
a phase difference of the incoming signals. Is it possible to tell the
difference between a positive and negative phase difference as as far as I can
see they will both always give the same voltage.

 

A 

Attached is one way of detecting positive or negative phase difference:
basically using two AD8302's to make a 360 degree phase detector.

Another way to do it is with an IQ demodulator (also attached).
Attachments:
Comments
Anonymous

  • I've been evaluating AD8302 temperature stability and temperature drift and room-temperature trim.  Look carefully at the phase versus temperature curves before you lock in your design if you require excellent temperature stability.  The nonlinear temperature coefficient values over the full 0C to +70C range make it very difficult to make the phase response stable to within 0.1 degrees using linear calibration even over a +/- 5C range. The ground pin temperature is the most-accurate temperature measurement point available once the device warms up to its quarter-watt operating temperature.

    I required insulation (as in precision frequency sources) over the AD8302 to prevent convection cooling which creates a device temperature measurement error and to create a uniform thermal gradient in the PCB under the chip.

    temperature_drift

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