Differential Output with two sine wave input. Can I add offset to both the sine wave going in positive and negative pin?

I am thinking of using a singe source 9V, and I plan to add DC offset to two sine wave input; one sine wave input goes to positive and the other sine wave goes to negative input of an opamp. The idea is to add DC offset to both the sine wave input and the output will be a DC coupled differential sine wave. If I don't add DC offset to the input sine wave, then the output will be a half wave as the opamp has a single source power.

Would there be any issue if I add DC offset to both the sine wave input?

I hope to hear your response. Any idea will be helpful.

  • +1
    •  Analog Employees 
    on Sep 3, 2021 4:31 AM

    Hi shurp,

    About having a DC-coupled differential output, what you would want to do is set the output common-mode voltage (Vocm) to half of your source so that you could maximize the positive and negative values of your differential sine wave output.

    So for a single source of 9V, you should set your Vocm to 4.5V. Your output will then look like as if your differential sine wave is dc-coupled to 4.5V.  

    Most differential amplifiers have Vocm input pin but if let's say you do not have any way of setting your Vocm then you can put DC offsets on your inputs. But keep in mind that what you will see on your output is the difference of the inputs and it also applies to any offsets added on the inputs.

    If you want to experiment more on Differential Amplifiers, you may want to try the ADI DiffAmpCalc (free download). See link below:

    ADI-DiffAmpCalc | Analog Devices

    I hope my answer helps. 

    Best Regards,

    Sham