# Input offset voltage

#### hp1729

Joined Nov 23, 2015
2,304
Let's say we have a non-inverting op amp circuit with a gain of 100 and an input offset voltage of 5 mV. A ground at the input would result in an output of 5 mV x 100 or 500 mV. Is that right?
An input pulse 1 mV high would still result in an increase at the output of 100 mV, right?

#### Alec_t

Joined Sep 17, 2013
14,007
A ground at the input would result in an output of 5 mV x 100 or 500 mV. Is that right?
Depending on the polarity of the offset the output could be +500mV or -500mV.
An input pulse 1 mV high would still result in an increase at the output of 100 mV, right?
Right.

#### #12

Joined Nov 30, 2010
18,224
Now, try it as a comparator running with the gain at open loop.
Set the input offset voltage at + 5 mv for the first test and - 5 mv for the second test.

Then try some scenarios for different input bias current, input bias current offset, input resistors, different noise levels, and different frequencies.

#### crutschow

Joined Mar 14, 2008
33,352
Depending on the polarity of the offset the output could be +500mV or -500mV.
............
Just to be clear to the OP, the offset polarity and magnitude for a particular op amp device is generally random with a voltage limit as given in the data sheet.

#### hp1729

Joined Nov 23, 2015
2,304
Now, try it as a comparator running with the gain at open loop.
Set the input offset voltage at + 5 mv for the first test and - 5 mv for the second test.

Then try some scenarios for different input bias current, input bias current offset, input resistors, different noise levels, and different frequencies.
True. I can see your point on a voltage comparator.

#### ramancini8

Joined Jul 18, 2012
473
hp1729---What happens if the gain is 1000 on a 5V supply?