Question on Optical Receiver Offset Cancellation !!

[suria3]

Guys,

Currently I'm doing research in Optical Receiver design consist of Transimpedance Amplifier and Limiting amplifier. I noticed that in the fully differential Transimpedance amplifier circuit design, there is a offset compensator at the output of the differential TIA and feedback to the dummy TIA.Then when it goes to the next stage of cascaded Limiting Amplifier, there is also another block of offset cancellation circuit which cancels any offset arised due to several stages of differential amplifiers. My question here is, is that necessary to have 2 offset cancelation circut i) after TIA ii) after LA in the receiver system or just need to have one at the LA stage. Which will be precise in the offset elimination. Please guide on this.

Thanks,
Suria

 

[pixel]

I think that one offset cancellation at the output of LA should be enough if offset value was small enough not to disturb operation mode of previous stages.