how to design current bias circuit???

[jlim]

Hello,
Can somebody help me that how to design input current bias circuit..??

 

[sarge]

Hi,
something like this:

You have a mistake in your schematic - gate and drain of NM3 must be shorted to form current mirror.

 

[prestonee]

Or use a bandgap to generate a reference voltage, then use a resistor dividers off it , then current mirrors as shown above.