differential amplifier

[prashant8kothari]

what is common mode output voltage in differential amplifier?

is it average of output voltages?

 

[91divine]

Output of Opamp based differential amplifier is the amplified value of the difference of voltage between both terminals (i.e. v- - v+ and amplified with the gain value)

see this image https://upload.wikimedia.org/wikipedia/commons/a/a2/Op-Amp_Differential_Amplifier.svg

 

[peeyushsigma]

common mode gain of differential amplifier is very less so that common mode output voltage is very less in practical and zero in ideal.

 

[betwixt]

Basically, the amount of output shift when both inputs are equally driven (or shorted together in some measurments). In an ideal situation, only the difference between signals at the inputs will be amplified and applying the same signal to both inputs will cause complete cancellation. Equal + and - amounts added together should give zero. In practice, there are slight manufacturing differences between the two inputs which stop them showing identical performance and also in some cases bias shifting due to current injection from two sources combining. These can make the output voltage shift even if the inputs should be cancelling each other.

Brian.

 

[crutschow]

what is common mode output voltage in differential amplifier?

is it average of output voltages?

If you are referring to a differential amplifier with differential outputs then yes, the common-mode output voltage is indeed the average value (DC) of the two outputs. An ideal differential amp will have the same voltage on both outputs if the differential input is 0V.