NEED YOUR HELP~want to amplify a signal that is DC value

[wilsons]

NEED YOUR HELP~

Hi，everybody! I got a problem now and need your help! I want to amplify an signal that it’s DC value maybe change, then I add a CAP to get the AC siganl. Next,I want to amplify that ac signal about 20dB. The output is diffrenetial, so I want to let CM level to be 0.9V. VCM is the reference given from outer. what kind of structures should I choose ? THANKS A LOT!

 

[arunkumar446]

Re: NEED YOUR HELP~

what structure ur asking about, is it about the structure of opamp or cmfb?
u specified dc may change, what dc is it?, if it changes why is it dc?

 

[wilsons]

Re: NEED YOUR HELP~

what structure ur asking about, is it about the structure of opamp or cmfb?
u specified dc may change, what dc is it?, if it changes why is it dc?

I want to know opamp's structure. The "DC" mean's the signal changed very slow compared the useful signal.

 

[arunkumar446]

Re: NEED YOUR HELP~

are you looking for a fully differential opamp? if so that slowly varying dc which would be common to both inputs wont be seen at the output, with the fully differential opamp we need to have a cmfb circuit.

 

[wilsons]

Re: NEED YOUR HELP~

no, I need to transform the single end signal to differential signal !

 

[jesseyu1984918]

Re: NEED YOUR HELP~

This would actually rely on your load, what do you want to drive and what performance do you want?