This is a constant gm current source.Caps are not used for start up here.C1 is a decoupling cap,but C2 will make the psrr much more worse for the noise in the power line will be shorted to the gate of nmos at the high frequency.
This is the Vdd independent biasing circuit. It should have a different startup circuit. The only reason I can think of to have those caps is for noise suppression as this circuit will be used for DC biasing.
C2 make the PSRR+ worse;C2 also filter the noise
how can I balance it?
another question, how can I calculate it?
if connect C2 to the gnd,is there any difference?
This is a constant gm current source.Caps are not used for start up here.C1 is a decoupling cap,but C2 will make the psrr much more worse for the noise in the power line will be shorted to the gate of nmos at the high frequency.