differential amplifier: Can anybody tell me how to set the common mode voltage in single to differential output amplifier?
Dear vasudev,
I have implemented a single ended to differential amplifier in the following way :
The circuit is composed of two amplifiers. One amplifier acts as a buffer and creates a voltage, Vout+. The second amplifier inverts the input and adds a reference voltage to generate Vout-. Both Vout+ and Vout- range from 0V to 2.5V. The difference, Vdiff, is the difference between Vout+ and Vout-.
Here, you can choose output common mode voltage Vcm (common mode voltage by resistors and Vref ). In simple case, Vcm= 0.5* Vref. so basically with proper resistors we can set up common mode.
Hope, my answer helps You.
:) :)
Dear Val Martin,
Yes I have a circuit in my mind. It is normal differential amplifier in which input is connected to only one input ,other is connected to biasing voltage.
Dear Vasudev,
this is what i have written in my reply, one input is kept at input and second given a Vref.
regards
Dear Anuraag
Thanks for your reply. You have mentioned with some resistors(how?) we can set common mode...This is the doubt what I have? exactly how we will set common mode voltage .It is not like fully differential output, in which we can set it by using CMD and comparator.
The resistors come in the equation and in the circuit, same voltage ( Vin= Vref) will appear for a value R3=R4, but if u put other values common mode will not happen.
I hope this page give you an idea about gain setting resistors for Diff Amp.
http://www.electronics-tutorials.ws/opamp/opamp_5.html
Dear Khan and Misra
First of all thanks .
I am not asking about Op-Amp case. Exactly I am asking about for the following circuit.
Please give me detailed explanation. I am not getting how to set the common mode for this circuit.
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