opamp open loop gain

Status
Not open for further replies.
S

shinulalu6

Newbie level 4
Joined
Mar 1, 2014
Messages
7
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
42
Why we are using RC network in the negative feedback to measure the op-amp open loop gain?
 

Without negative feedback the finite offset voltage - together with the very large open-loop gain of the opamp - will drive the output into saturation, thus disabling any small-signal gain measurement.
Fot this reason we provide dc feedback (which drastically reduces the dc gain) but in addition we use a capacitor for shorting the feedback signal for rising frequencies.
As a consequence, we cannot directly measure or simulate the gain at DC - however, if the capacitor is large enough the signal feedback (ac) is not effective for frequencies below the open-loop cut-off frequency.
Hence, we can extrapolate the gain down to dc.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…