Question about transconductance gain of an amplifier.

Thread Starter

tadm123

Joined Nov 20, 2013
43
As I understand it the intrinsic gain of an op amp is the open loop gain, and the overall gain is the closed loop gain with feedback.

But my question is, what exactly is the transconductance gain? Is that the intrinsic gain of the amp? And if it isn't, how can I calculate the gain of the amplifier itself?


I hope the question makes sense, thanks in advance.
 

#12

Joined Nov 30, 2010
18,076
Transconductance? Change in current for change in voltage? Operational amplifiers are voltage driven. They supply as much current as the load needs, within the limitations of the current the chip can deliver. If you want transconductance, you can get a transconductance amplifier that looks very much like an operational amplifier but works according to your expectations.
 

LvW

Joined Jun 13, 2013
840
Yes - as indicated already by #12, there are some integrated amplifiers which - sometimes - are called "operational amplifier", although this is somewhat misleading.
At first, there is the "operational transconductance amplifier" (OTA) which is voltage-driven with a current output.
Hence: output/input=current/voltage=transconductance.
By the way: This also applies to transistors which are characterized by their "transconductance" which is identical to the slope of the Ic=f(Vbe) characteristic.
(The term "transconductance gain" is not correct).
 
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