hi,all
  i am designing a 2.5Gbps Transimpedance Amplifier currently, i utilize the cascode topology, the input impedance is greatly reduce to 1/gm, so the input pole is moved far away, however, i found the current sinker contributes large noise current to the input node directly, i have try to increase the Vgs(of course, i still make sure that it is in saturation) and minimize the W/L for a required current, but it still produces near 50% of total input rms referenced noise current. what methodes or techniques you guys would take to reduce its noise based on your experiencement, please let me know, i would really appreciate it, thanks a lot!

best Regards
Nio Lin

Dear Jerry,
   thanks for your reply!
   the prototype i used is illustrated as attachment, currently i used the 0.35u CMOS process to design 2.5G/ 4G TIA, except the shunt-shunt feedback structure with cascode (regulated) as input stage, i do not have other solution.

Nio Lin