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how to obtain good PSRR for two stage amplifier?

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alicia8283

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ahuja psrr

how to obtain good PSRR for two stage amplifier?
My stability is ok as i have put compensation cap at the 2nd stage..
thanks in advance..
 

psrr 2 stage

alicia8283 said:
how to obtain good PSRR for two stage amplifier?
My stability is ok as i have put compensation cap at the 2nd stage..
thanks in advance..
Click to expand...

a paper has explained it.
<<design techniques for cascoded cmos op amps with improved psrr and common-mode input range>> by david b.ribner & miles a.copeland
 
psrr + two stage

Increasing the channel length of your second stage amplifying transistor will help you get bigger positive PSRR. You can check Allen's book on this issue
 

Poor PSRR of the basic two stage op-amp can be attributed to the compensation capacitor.

Alternative compensation techniques such as Ahuja Compensation and Cascoded Miller Compensation will help achieve better PSRR performence at high frequencies.

I hope it helps.

With Regards
Sachin
 

When using a class A output, use an nmos driver with a pmos output. This isn't noticeable in AC sim, because of the small signal linearization, but for transient PSRR simulations (takes a lot of time, but these include the non-linearities of the transistors)
this is clearly visible.

2nd tip is isolating your opamp from the supply, by
-cascoding
-using a extra regulator which supplies your opamp. This can easily boost your PSRR by 30..50 dB.

br, Jef
 

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