# Differential Amplifier

#### farman99

Joined Apr 5, 2016
6
if there are two single inputs to a difference amplifier are Va and Vb. And these inputs are simple function of cos or sin with different frequency and phase. then the difference of these is very simple by Vo=Vb-Va.
However, what if the two inputs of the diff amplifier are infact the outputs of two different mixers (each mixer output has sum and difference components). Can a single amplifier on its own gives single output based on the given inputs? OR multiple difference amplifier is needed to integrate?
Also please state that in terms of size, whether the size on chip will be greater?
Any alternative to this type of operation if someone can provide, please state. Thanks

#### hp1729

Joined Nov 23, 2015
2,304
if there are two single inputs to a difference amplifier are Va and Vb. And these inputs are simple function of cos or sin with different frequency and phase. then the difference of these is very simple by Vo=Vb-Va.
However, what if the two inputs of the diff amplifier are infact the outputs of two different mixers (each mixer output has sum and difference components). Can a single amplifier on its own gives single output based on the given inputs? OR multiple difference amplifier is needed to integrate?
Also please state that in terms of size, whether the size on chip will be greater?
Any alternative to this type of operation if someone can provide, please state. Thanks
Yes, it will be a single output, maybe not what you expect. My suggestion is to build it and see if it does what you want.

#### GopherT

Joined Nov 23, 2012
8,012
if there are two single inputs to a difference amplifier are Va and Vb. And these inputs are simple function of cos or sin with different frequency and phase. then the difference of these is very simple by Vo=Vb-Va.
However, what if the two inputs of the diff amplifier are infact the outputs of two different mixers (each mixer output has sum and difference components). Can a single amplifier on its own gives single output based on the given inputs? OR multiple difference amplifier is needed to integrate?
Also please state that in terms of size, whether the size on chip will be greater?
Any alternative to this type of operation if someone can provide, please state. Thanks
The complexity of the input has no influence on the amplifier needed. Your question is like asking, can I use the same amplifier for rock music and classical music.

The only issue would be slew rate. If some of the complex signals have very fast rising or falling edges, then that is more of a question of picking the right components for your signal - adding more stages usually hurts speed rather than helps.

#### farman99

Joined Apr 5, 2016
6
Thanks for your suggestions but let me elaborate my question by looking at the attached model, can a single differential amplifier perform the complex inputs as show in the attachment?

--Sorry the file cannot be uploaded

#### Willen

Joined Nov 13, 2015
327
Thanks for your suggestions but let me elaborate my question by looking at the attached model, can a single differential amplifier perform the complex inputs as show in the attachment?

--Sorry the file cannot be uploaded

#### dannyf

Joined Sep 13, 2015
2,197
Can a single amplifier on its own gives single output based on the given inputs?
Yes. The amplifier doesn't know nor does it care, where the signal comes from.

#### hp1729

Joined Nov 23, 2015
2,304
Thanks for your suggestions but let me elaborate my question by looking at the attached model, can a single differential amplifier perform the complex inputs as show in the attachment?

--Sorry the file cannot be uploaded
You can spend a week here asking questions or an hour or so building it to find out.