questin in fully op amp ?

[wael_wael]

hi every body

i have 2 stages fully differential op amp, i want increase the current in second stage. in fact when i increase the current in the bias circuit the current in first stage increase but in second stage not increase much . so could some one help me and give me any idea to increase the current in second stage
thanx

 

[airboss]

Hi,

just few thoughts up in my head.

1) test each stage separately. say, only work on your 2nd stage and see if increasing the current in your bias ckt changes anything in your main ckt.

2) i think it's a little hard to help you w/o your schematic. can you upload ur schematic?


cheers

 

[qqic]

separate bias

 

[nxing]

Check the second stage's input bias point.

 

[RDRyan]

If you use current mirror, then change the W/L of the current mirror in the sencond stage. The current bias circuit should not change. I think.

Ryan