input and output impedence of opams

@cranky-E9J79q • Oct 22, 2024

Oct 22, 2024

1.2K

Hey all,
I need major help with finding input and output impedances of opams.I undersatnd that to find Zin,make vout=0 and put a source at input.But still things aren't clear for me.Consider the inverting amplifier in <a href="https://en.wikipedia.org/wiki/Operational_amplifier" target="_blank" rel="nofollow noopener noreferrer">Operational Amplifier</a> link.Can someone help me find the Zout?Is it Rf or zero?😒

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Harshad Italiya

@harshad-ukH5ww • Jun 24, 2010

as per my knowledge there is no load connected so it should be zero.. because you see ideally Zout should be as low as possible near to Zero.

Zout= Rload/1+Aol.

In this case no RL so it should be zero.
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cranky

@cranky-E9J79q • Jun 25, 2010

is there any other way or some kind of analysis we can do?
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shreyasm89

@shreyasm89-jGobVm • Jun 25, 2010

yes there is...actually if you refer to any good book on OP_AMPS they will give you the detailed analysis. From wat I know, for finding Ri u should ground one i/p terminal of the op-amp and then analyse the the remaining part. As for o/p impedance, short the i/p and connect the source at the o/p. Then do analysis of the circuit by considering i/p as zero. you have to consider the current flowing through the series o/p resistance. Actually when u refer the books they'll give u the equivalent circuit of an op-amp which if u go through once, calculating both the impedances will be child's play.
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cranky

@cranky-E9J79q • Jun 27, 2010

thank you😀..will get back to you.
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