From: John Woodgate
Subject: Re: output impedance
Date: Thu, 7 Nov 2002 20:12:13 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Thu, 7 Nov 2002 21:29:35 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Winfield Hill
wrote (in ) about 'output impedance', on
Thu, 7 Nov 2002:
>> Mick McGrath wrote:
>>> I have learned that the output impedance of an ideal current
>>> amplifier should be infinite. How can any current flow through
>>> infinte impedance?
>> The ideal voltage is infinite also.
> Usually we're referring to current sources when making such
> a statement: an infinite resistance powered from an infinite
> voltage. But an infinity that follows ohms law, in that the
> voltage is V = IR, or I times infinity. :-) As Kevin says,
> nonsense. Hah, a simple feedback-controlled current-source
> circuit does very well in practise.
I'm very surprised to find you calling an ideal theoretical concept
'nonsense'. I think it probably doesn't represent your true view. Do you
accept the 'ideal op-amp' as a theoretical concept?
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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