Question regarding optimizing gain

[ricopt]

Anyone out there, Can tell me how do i know that i have already achieved maximum transimpedance gain ?

All i know, i need to fix my L(transistor)=0.18um, and my input current as 30uA.

Circuit


Bandwidth and gain


Currently, i am able to achieve 61dB for this design for 1.25 Gbps.But i don't know how do i know that it is maximum ?does it have anything to do with bandwidth ?or noise ?:???::-(


Your response are greatly appreciated.Thanks

 

[leo_o2]

Cascode structure will help to increase gain.

 

[ricopt]

ya, but my problem is i don't know which value is optimized for my design.Since W value for transaistors MN! and MN2 will effect the gain, and R2 and Rf will also affect my gain.I don't know which to adjust so i can max my transimpedance gain