transistor sizing and transimpedance gain

[ricopt]

Can anyone tell me how W/L affect transimpedance gain ?
From my simulation result, If i increase W/L, transimpeance gain will decrease
Is it correct ?
is there any reference i can find ?

 

[masa_2010]

you can check this application note:

**broken link removed**

Hope this help

---------- Post added at 03:03 ---------- Previous post was at 02:58 ----------

Tell me what you are trying to do ? are you trying to design a transimpedance amplifier ?

 

[leo_o2]

What do you do with the L? For common source stage, the gain will depend on gm.ro. If you have same w and smaller L (though w/L is increased), gm will increase by a little while ro will be reduced more. And gm.ro might be smaller.

 

[ricopt]

For L, i make it minimal 0.18um

---------- Post added at 15:53 ---------- Previous post was at 14:50 ----------

you can check this application note:

**broken link removed**

Hope this help

---------- Post added at 03:03 ---------- Previous post was at 02:58 ----------

Tell me what you are trying to do ? are you trying to design a transimpedance amplifier ?

Ya bro, doing transimpedance amplifier

---------- Post added at 15:55 ---------- Previous post was at 15:53 ----------

What do you do with the L? For common source stage, the gain will depend on gm.ro. If you have same w and smaller L (though w/L is increased), gm will increase by a little while ro will be reduced more. And gm.ro might be smaller.

Bro, what if i have the same L with 0.18 while i set my W=45 and 44, which one will have greater gain ?

 

[leo_o2]

If all other parameters are same, of cource bigger W will have bigger gain.