How to measure and improve PSRR in opamp design

[dayang]

Hello,
My target is to design a opamp in 180nm 1.8v power supply.The input and output need rail to rail.My question is about the PSRR,How to measure it(use a close loop configuration or a open loop configuration)? How to improve it(just simply increase the channel length? is there any guideline about it ? I have read the posts here but still not understand it clearly, Help!!

REGARDS

 

[tavakoli]

Re: Help in Opamp Design

it could be improved by using cascade cofigurations that shield the circuit from power supply ...

 

[dayang]

Re: Help in Opamp Design

it could be improved by using cascade cofigurations that shield the circuit from power supply ...

The question is that when you use a rail to rail input configuration , there is not enough vlotage to hlod the cascade current mirror to work correctly.

 

[Btrend]

Re: Help in Opamp Design

Hello,
My target is to design a opamp in 180nm 1.8v power supply.The input and output need rail to rail.My question is about the PSRR,How to measure it(use a close loop configuration or a open loop configuration)? How to improve it(just simply increase the channel length? is there any guideline about it ? I have read the posts here but still not understand it clearly, Help!!

REGARDS

PSRR=20*log(ΔVout/ΔVcc)
so use closed loop, introduced AC signal at VCC and then probe Vout

 

[dayang]

Re: Help in Opamp Design

Hello,
My target is to design a opamp in 180nm 1.8v power supply.The input and output need rail to rail.My question is about the PSRR,How to measure it(use a close loop configuration or a open loop configuration)? How to improve it(just simply increase the channel length? is there any guideline about it ? I have read the posts here but still not understand it clearly, Help!!

REGARDS

PSRR=20*log(ΔVout/ΔVcc)
so use closed loop, introduced AC signal at VCC and then probe Vout

Yes ,I got it and final PSRR is about 31dB, thank you very much