sry forgot to mention cant use resistors...
as of now i have done using a diode connected pmos(with a different W/L) and gave its gate volatge...
but the matching isnt perfect
Instead, try and use a (small) pmos with its gate connected to GND or to one of the n-bias voltages. Or an nmos with its gate connected to the upper p-bias voltage, or to VDD.
Hi Chirag,
As u need good output swing, you can go with Low voltage Cascode Current Mirror circuit mention in Razavi.
One more point : In your circuit How You are generating gate bias for your PMOS tail current mirrors. It looks like your PMOS (diode connected 3rd branch) is off.