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I'm using this TL071 op-amp datasheet and I am trying to find the op-amp output impedance on the datasheet so I can calculate the output impedance when used in amplifier/peak detector circuit. Do I need to calculate the output impedance from one of the other characteristics on the data sheet or am I missing something?

Many thanks in advance!

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  • \$\begingroup\$ You really shouldn't be using a 741. \$\endgroup\$
    – Hearth
    Commented Apr 4, 2020 at 17:52
  • \$\begingroup\$ Sorry, just edited its a TL071, to be used in a peak detector circuit. \$\endgroup\$
    – arry_h
    Commented Apr 4, 2020 at 17:53
  • \$\begingroup\$ Oh, much better choice. \$\endgroup\$
    – Hearth
    Commented Apr 4, 2020 at 17:55
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    \$\begingroup\$ You realize that when applied in a closed loop, the output impedance is usually less than an ohm across a broad range of operating frequencies. \$\endgroup\$
    – Andy aka
    Commented Apr 4, 2020 at 17:57
  • \$\begingroup\$ Thank you for all the responses. Yeah I now realise, when implementing it practically, I shouldn't consider it too much - thanks again. \$\endgroup\$
    – arry_h
    Commented Apr 4, 2020 at 18:01

2 Answers 2

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You won't find it if it's not explicitly listed (which is rare). Typically Zo of the order of a hundred ohms for that type of op-amp.

Closed loop output impedance, of course, is almost zero.

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    \$\begingroup\$ Many thanks for your answer, Sir. \$\endgroup\$
    – arry_h
    Commented Apr 4, 2020 at 18:03
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The output impedance in a closed loop situation will increase with frequency because as frequency increases the feedback reduces. The feedback factor in an amplifier, for instance, is equal to 1 + BAo and as frequency increases, the open loop gain,Ao rolls off. You could say that the output impedance is simulating an inductance which also has an increasing impedance with frequency.

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