Phase Sensitive Detection methods

Discussion in 'General Electronics Chat' started by hunterage2000, Jan 28, 2012.

  1. hunterage2000

    Thread Starter Active Member

    May 2, 2010
    Hi, I'm working on different ways to do PSD using a 3 op-amp inst amplifier. I have done it with a CMOS 4053 switch with 555 timer and with a AD630 mod/demodulator device. Is there any other effective ways to do this?
  2. hunterage2000

    Thread Starter Active Member

    May 2, 2010
    Does anyone of the 86 that viewed this post know or what!
  3. BillB3857

    Senior Member

    Feb 28, 2009
    Phase-locked-loop IC's will do phase detection and provide an output voltage proportional to the phase displacement. Also, a Google search of Phase Detector will give a variety of suggestions.
  4. bertus


    Apr 5, 2008

    Did you have a look at the quadrature demodulation?
    On this page there are some examples:

    A quadrature demodulator provides a signal with a phase relative to the reference oscilator.

  5. t06afre

    AAC Fanatic!

    May 11, 2009
    You have also a digital way of doing this. Used in digital lock-in amplifiers.
    The lock-in amplifier is basically a synchronous demodulator followed by a low-pass filter. The measured signal and the reference signals are sampled. And after that all is done digitally. Signals are multiplied sample by sample. Then run through a low pass filter. I once made an AC skin conductance meter using a sound card and Labview. Using the latter technique. ​
  6. arwooldridge

    New Member

    Nov 28, 2009
    The phase sensitive detector is basically a 4 quadrant multipler.
    Phase lock loops often use a simple exclusive OR function to approximate it.
    A simple one op amp and one switch to ground circuit will do an Analogue x digital multiplication or phase sensitive detection.
    Take a standard inverting op amp circuit with gain of -1.
    disconnect to +ve opamp input from ground and connect it to the Analogue input via a resistor, add the shunt switch to ground at the +ve input of the op amp.
    When the switch is on the circuit has a gain of -1.
    When the switch is off the circuit has a gain of +1.
    If the signals are in phase you will get a full wave rectified version of the input.
    If they are out of phase the output polarity will be reversed.
    The switch is driven from the signal you want to phase detect to.
    Follow up with some filtering as necesary.