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AS Op Amps trouble...

Discussion in 'General Electronics Discussion' started by Callum, Jan 20, 2013.

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  1. Callum


    Jan 20, 2013
    Hello there, I don't know if anyone can help me but I seem to be struggling with Op Amps at AS level. I'm unsure whether there's a correct way to measure the input impedance or whether or not it's high/infinite? Also, how would I calculate the output voltage when I have the gain and an input voltage?

    Cheers for any future replies, Callum :)

    I do have a little parameter, value table with; Output Impedance, Input Impedance, Open Loop gain, GBP and slew rate if that helps.
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    Input impedance for a standard op-amp is very high; it's practically infinite for FET-input op-amps. That's the impedance presented by the op-amp at its inverting and non-inverting inputs. The input impedance of an op-amp-based CIRCUIT may not be so high; it depends on the other components.

    The basic definition for an op-amp is that the output voltage is equal to the differential input voltage (that is, the voltage at the non-inverting input minus the voltage at the inverting input) multiplied by the voltage gain. In practice there are other factors involved, such as input offset voltage, but that is the basic definition of what an op-amp does.
  3. Callum


    Jan 20, 2013
    Thanks a lot!
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