# What is open loop differential gain?

#### Elevon

Joined Jun 7, 2020
16
Simple question - what is open loop differential gain?

What is the difference between open loop gain and open loop differential gain? I cant find a definition for the latter anywhere.

#### Papabravo

Joined Feb 24, 2006
14,244
It is the gain applied to the voltage difference between two input voltages with no feedback from the output to the inputs. A typical open loop differential gain might be 200,000. In a practical circuit you would see the amplifier output at the negative rail if the difference is negative, At the positive rail if the difference is positive. In a very small range from [-60 μV,...,60 μ], assuming ±12 VDC rails, there would be a straight line connecting the negative and positive rails with a slope of 200 mV/μV. That is what an open loop differential gain of 200,000 will get you.

#### LvW

Joined Jun 13, 2013
1,078
Simple question - what is open loop differential gain?
What is the difference between open loop gain and open loop differential gain? I cant find a definition for the latter anywhere.
Both are identical.
We speak about "open-loop gain" only if we have to compare it with "closed-loop gain". And in such a case, we generally have to input ports (one inverting and one non-inverting). Best example: Operational amplifier.
Because of the two input nodes we define the voltage between boith inputs as "differential input" - resulting in "differential gain."