Re: difference between instrumental amplifier and operational amplifier

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#886

From: Mike McCarty
Date: Tue, 14 Mar 2000 00:00

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In article <38CE6346.C09FF5C5@calweb.com>,
William Janssen  <billj@calweb.com> wrote:
)
)Also, The op amp input impedance is not the same on the + and - 
)inputs. If you are trying to use a balanced input the op amp.
)won't be balanced.

Untrue. The *circuit* the op-amp is in gives unbalanced impedance
often, but op-amps themselves have balanced input impedances.

)You can make a instrumental amp from three op amps properly connected
)so that only the + inputs of the op amps are used as inputs which
)gives a balanced and high impedance input.

This is true, but the reasoning is incorrect.

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From: jmccarty@sun1307.ssd.usa.alcatel.com (Mike McCarty)
Subject: Re: difference between instrumental amplifier and operational amplifier
Date: 2000/03/14
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