How to enhance the DC gain of an CMOS opamp?

[leonken]

Are there some methods to enhance the gain of an CMOS opamp?
I designing an CMOS opamp. The architecture is a simple OTA with an Nmos diff. pair.

 

[OpAmp]

The first method is to use cascode transistors instead of simple common source amplifier.

Then, you can use Gain-boosting method which is described in almost all CMOS analog circuit design books.

OpAmp

 

[jwfan]

Ordinarily, decrease the bias current will increase the gain slightly. Or change the W/L to increase the Ro, if your don't want to change the whole topology which have been provided by OpAmp.

 

[jluhzw]

YOu can get the methods by refering the documents and the books.
Pray's book "analog integrated circuits analysis and design"
Allen's book "cmos analog circuits design".

 

[Chethan]

If you dont want to change the architecture then there are two ways of increasing gain
1)Decrease the biasing current
2)Increase the W of the input n channel diff amplifier

 

[sunking]

muti-stage opa too