Folded Cascoded Opamp

[alifathi]

Hallo
I have desigend a folded cascoded op amp work at very high frequancy 1Ghz
with .13micro technology.and it gives good resultes but if i change the baise voltage just 1 mv Ex (700m to 699mv) the output CM level changing completley is that normal.if not do anybody know what is the problem.I didnot add CMFB circuit yet.

 

[khouly]

if it is fully differential OPAMP , u need to add the CMFB to stabilize ur operation but the 1 mv is very strange

khouly

 

[tedd]

without CMFB, the output CM voltage is changed with the input voltage, it it normal