Sqaure wave

Discussion in 'General Electronics Chat' started by Annu007, Jun 12, 2006.

  1. Annu007

    Thread Starter Member

    Jun 12, 2006
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    I need to calculate an average value of a square wave (Frequency- 48MHz).

    Amplitude- 5V.
    50% duty cycle.
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,163
    1,796
    The frequency is not relevant. The average of a square wave with a 50% duty cycle that swings between 0V and +5V is V/2 or 2.5 volts. There is a more complicated derivation involving the integration of a pair of unit step functions which gives the same result. Another derivation is to integrate V(t) with respect to t divided by T, the length of a single period.

    There is also the statistical approach which is to take the Expected Value of the Voltage. It is 1/2*5V + 1/2*0V = 2.5 Volts. This is the same case as a Bernoulli trial
     
  3. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    Of course this is true for a square wave that goes from 0V to +5V. If it was symetrical around 0V ie. -2.5V to +2.5V then the average would be zero.

    Simple answer for a 50% duty cycle is 1/2 the peak to peak value. This also holds true for any symetrical wave form with a 50% duty cycle.
     
  4. Annu007

    Thread Starter Member

    Jun 12, 2006
    11
    0
    Hello,
    Is there a circuit I can use (like a filter) with which I can measure the DC value of this wave?

    Regards
     
  5. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    Yes. A DC multimeter will do that. It will measure the DC average of the signal.
     
  6. Papabravo

    Expert

    Feb 24, 2006
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    Assuming that it can follow the 48 MHz. signal. It would not surprise me that a typical multimeter would read something smaller than V/2.
     
  7. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    605
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    ooooppppsss missed that little detail.
     
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