What are the rules for biasing an OP??

[zhangjavier]

As I see that in a OP the transistors are usually stacked. Are there some basic rules to follow to design appropriate bias circuits for these transistors??

 

[jimway]

How to bias a OP??

It depends on the spec like output swing or linearity.

 

[DZC]

How to bias a OP??

The general goal is to bias the transistors which signal travels in the saturation region to work with large gain and good linearity.Better to save more swing at the same time.

 

[zhangjavier]

Re: How to bias a OP??

The general goal is to bias the transistors which signal travels in the saturation region to work with large gain and good linearity.Better to save more swing at the same time.

I just wonder the structure of the bias circuit for a OP amplifier. How to bias each transistor in a stacked configuration??

 

[bigkitty]

Re: How to bias a OP??

You can bias the cascode transistor by a diode which has a 1/4~1/7 W/L of the current source transistor. 1/4~1/7 W/L determine the output swing.

 

[jimway]

Re: How to bias a OP??

The general goal is to bias the transistors which signal travels in the saturation region to work with large gain and good linearity.Better to save more swing at the same time.

I just wonder the structure of the bias circuit for a OP amplifier. How to bias each transistor in a stacked configuration??

There are several ways to bias high swing cascode current source such as self-biasing.

 

[adsl]

How to bias a OP??

You can refer to some advanced current mirror configuration, such as wilson.