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Can opamp work this way ?

  1. Aug 30, 2011 #1
    can opamp work this way ??

    can opamp work this way ..?

    when i input 2volts the output is 4volts , when i input 5 volts the output is 25 volts

    in simple words can opamp takes the square of input signals ??

    is it possible ? i know how it work as differentiator, integrator, Summing amp but what about squaring ?
     
  2. jcsd
  3. Aug 30, 2011 #2
    Re: can opamp work this way ??

    To obtain squares and square roots you need a four quadrant multiplier, such as the MC 1494.

    There is an analog solution using the square law characteritic of diodes or FETs but they are tricky to set up.
     
  4. Aug 30, 2011 #3
    Re: can opamp work this way ??

    can you please help about using diodes for squaring and square rooting ? what technique we use for squaring ?

    like if we Apply n volts the output must b n*n
    or simply sum of n times ,
    like if we apply 5 volts the output must be 5+5+5+5+5
     
  5. Aug 30, 2011 #4
    Re: can opamp work this way ??

    Review the circuit in

    http://www.analog.com/library/analogDialogue/bestof/pdf/19_1.pdf

    The transistors are working in essentially the transdiode configuration, because they give superior diode lograrithmic performance than real diodes. Look at the equations Eq (1) thru (6). The (kT/q) log function is the ideal diode I-V response.

    Bob S
     
  6. Aug 30, 2011 #5

    berkeman

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    Staff: Mentor

    Re: can opamp work this way ??

    Are you constrained to using opamps? Can you use an ADC + Microcontroller + DAC instead?
     
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