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phase comparator

Discussion in 'General Electronics Discussion' started by fatimak, Nov 25, 2008.

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  1. fatimak

    fatimak

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    0
    Nov 25, 2008
    I need to find the phase difference between two 125 Hz signals.I need an analog IC that would work as a phase comparator .My search uptil now have only produced digital phase comparator ic's or ones with a higher bandwidth.
    I have also read about using an analog multiplier for the purpose but cant seem to find an IC for that.
    Any and all help is greatly appreciated
     
  2. neon

    neon

    1,325
    0
    Oct 21, 2006
    2 AND gates cross coupled and apply the input thru cap and a res. pull up. THAT IS THE CHEAPEST AND IT WORKS. Beware there are forbidden states into the setup at power on .
     
  3. fatimak

    fatimak

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    0
    Nov 25, 2008
    thanks Neon but the only problem is that i need an analog solution to the problem.The AND gates would require a TTL input wouldnt they.
     
  4. neon

    neon

    1,325
    0
    Oct 21, 2006
    Well yes but you have not mentioned that before.
     
  5. mansoor ahmed

    mansoor ahmed

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    Jul 15, 2009
    Almost i am encountring the same problem i.e iam trying to find an analog ic to compare phase difference between two signals of 50 hz to be use in automatic synchronization of generators running in paralell yet not found.I hope you have found if so then also tell me as quickly as possible.
     
    Last edited: Jul 15, 2009
  6. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    I'm sure that neon's suggestion can be applied to line-level analog signals using CMOS gates running at low supply voltage (3V). Use resistor dividers to hold the inputs at half supply voltage and send the signals in through caps. That should make them quite sensitive. Filtering the output then gives an analog signal out.
    Otherwise maybe this IC could be used: .fairchildsemi.com/ds/MM/MM74HC4046.pdf
     
  7. amdNRA

    amdNRA

    50
    0
    Sep 3, 2009
    In addition to the previous posts I suggest you square up the analog to digital by first using a comparator (LM339) with hysteresis or a Schmitt trigger (CMOS 4093), then you input the signals to a bit comparator made up of a CMOS Exclusive OR such as a 4070. The output of the 4070 should be proportional to the phase difference.
    Hope this helps, Gil. :cool:
     
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