🚀 go-pugleaf

In <1jkrvsINNrmu@usenet.INS.CWRU.Edu> ah335@cleveland.Freenet.Edu (Richard Banks) writes:


>What is the average resistance range in ohms of R_out on a op amp.

>Thanks.

In most cases the output resistance of an op amp is formed by the output 
resistance of a (bipolar) transistor in parallel with its biasing circuit.
Depending on the type of op amp (especially its current consumption and
the process parameters) the output resistance therefore can vary between 
10 kilohms and 100 Megohms.

But ....

When the op amp is used in a negative-feedback configuration the output
resistance of the total circuit lowers due to the loop gain in the circuit.

For example:

Suppose you apply an ordinary op amp as a voltage follower, i.e. you connect
the output to the negative input the output resistance can be a few ohms. As
an op amp in most cases is used in a negative-feedback configuration it often
is said that the op amp (itself) has a low output resistance. Now you know why.

Good luck.

Wouter