Single Ended Switched Capacitor Opamp to Differential Conversion

[Puppet123]

Single Ended Switched Capacitor Opamp to Differential Opamp Conversion

Hello,

I designed a single ended opamp sample/hold switched capacitor amplifier with sample capacitors and switches.

I want to convert it to a differential opamp.

What do I have to do to the current, sampling capacitances, switches and the load capacitances ?

I am guessing (please tell me if I am right) - double the current, 1/2 the sampling caps, 1/2 size of switches, double the load capacitance ? Also, add Common Mode Feedback. Is this correct ?

Is this correct ? Did I forget anything ?

Thank you.

 

[frankrose]

Would be easier to answer if you shown before/after pictures. I am not sure you have to halve the size of everything and double the currents...

 

[Puppet123]

Hello,

Thank you for your response.

It is a flip around MDAC for Pipeline ADC.

See attached picture. I want to make this fully differential.

Do you have any papers, thesis, reports, or other resources that can tell me how to do that ?

Thank you.

 

[frankrose]

You know, I don't see the load capacitance on this, and not this is my only problem. Probably the differential version is not a big deal, but simply I just don't know it.
Did you do some research on it? It would be the best. Probably others have done it already, outside of this forum.
My other thoughts, concerns you could explain:
- why would you double the currents? I don't know any specification, I can't tell you.
- halve the caps depends on where they were originally, can't just halve every caps I think...why double the load caps?
- why halve the switches??
- ah, common-mode feedback definitely you will need