Op-Amps Concept Clarification

[LickMyEyeball]

I have been given a question regarding op-amps. In the figure however, there are elements which have not been introduced nor explained in the chapter. Please refer to the attached image.

(Image taken from "Microelectronic Circuits",by Sedra and Smith, 6th Ed., page 58.)

In the figure there are statements beside each internal independent current source. What is "G_m"? Are these current sources supplying power needed by the op-amp? Perhaps it is a part of gain? Can it be related to A?

I do not know. Any detailed conceptual explanation would be greatly appreciated, as I need to be able to use these values quantitatively and confidently!

Thanks for your time and patience.

 

[berkeman]

I have been given a question regarding op-amps. In the figure however, there are elements which have not been introduced nor explained in the chapter. Please refer to the attached image.

(Image taken from "Microelectronic Circuits",by Sedra and Smith, 6th Ed., page 58.)

In the figure there are statements beside each internal independent current source. What is "G_m"? Are these current sources supplying power needed by the op-amp? Perhaps it is a part of gain? Can it be related to A?

I do not know. Any detailed conceptual explanation would be greatly appreciated, as I need to be able to use these values quantitatively and confidently!

Thanks for your time and patience.

The G_m are gain multiplier values. They have units of A/V, so they take a voltage as an input, and give you current as an output. Those are "voltage controlled current sources".

 

[phyzguy]

Gm is also typically called "transconductance"

http://en.wikipedia.org/wiki/Transconductance