Help me understand class AB output stage of this circuit

[opamp741]

Class AB output stage

Dear Frds,
please help me understanding following circuit.
It is a class AB stage that can be used as a output buffer stage in opamp.
But I am not sure how does it works and how to identify bias point for it.

 

[sunking]

Re: Class AB output stage

igore the body effecct, notice the Vgs of M5 M4 M2 M1,
you will get Vgs5+Vgs4=Vgs2+Vgs1.

so the bias current is bias by M3.

 

[avinash]

Re: Class AB output stage

just refer to book by allen and holberg on CMOS analog circuit design