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Subject: Re: output impedance
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Thu, 07 Nov 2002 16:01:36 GMT
NNTP-Posting-Date: Thu, 07 Nov 2002 17:01:36 MET
"Mick McGrath" schrieb im Newsbeitrag
> I have learned that the output impedance of an ideal current amplifier
> should be infinite. How can any current flow through infinte
In a current source the internal resistance is in *parallel* to the ideal
Io = (Uout/Rload)+(Uout/Ri)
Rload is the resistance of the load, Uout is the voltage across the load, Ri
is the inner resistance of the current source,
If Ri is infinite, the output current is independent of the load resistance
and that is what we expect from a current source.
Ohm's law isn't it.
You can determine Ri with 2 measurements:
Rload = 0 short circuit current is Io. Io be 1.0000mA
Rload = 10k now we measure 0.9980mA.
Ri = 9.98V/(1-0.998)mA
Ri = 4.99M
electronic hardware designer
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