Psrr simulation operational amplifier !

[biolycans]

Hi,

I designed an operational amplifier CMOS two stage. I want to simulate the PSRR. Vdd = 2.5 V and Vss = -2.5 V, are the voltages supply of the opamp.

What configuration and values in the input should I choose for the simulation of the PSRR ?

Regards,

Joaquin

 

[Dominik Przyborowski]

You need to do a simple ac simulation with power supply ac=1 and look on the output of closed loop opamp.

 

[biolycans]

You need to do a simple ac simulation with power supply ac=1 and look on the output of closed loop opamp.

Hi, thank you for your response. I did this:

1) the inverting input is connected to the output.
2) the not inverting input is connected to a offset to balance the opamp. Then I put an AC 1 in serie with Vdd.

the plot has an amplitude of -80 dB and then increase. Is this correct ?

Regards,

JC

 

[Dominik Przyborowski]

In fact PSRR=-dB20(VF("/your_output_net"))

For low frequencies PSRR should be high and start decreasing around opamp dominant pole.