Re: Loading Effect in Feedback

From: Jim Thompson (thegreatone_at_example.com)
Date: 12/08/04 

Date: Wed, 08 Dec 2004 08:26:38 -0700

On Tue, 7 Dec 2004 20:09:52 -0600, "Zhiheng Cao" <cao@ece.utexas.edu>
wrote:

>I am a student studying analog circuits and I am having hard time
>understanding loading effect in feedback.
>
>Some books say when we cut the loop, we need to load
>the output of the opamp with feedback network beta and the opamp input
>behind it, but we can set the voltage (by the feedback) at the opamp
>input using an ideal voltage source.
>
[snip]
>
>I am sorry if my explanation is too confusing.
>
>Thank you for reading my post.
>

Look up Middlebrook's method, where the loop is NOT broken.

Then study the LOOPGAIN part on my website. The part implements the
Middlebrook procedure for use in a Spice simulator.

                                        ...Jim Thompson 

-- 
|  James E.Thompson, P.E.                           |    mens     |
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