How to increase the psrr of a bandgap?

[avinash]

i have designed a simple first order bandgap .psrr of the bandgap is 60dB.psrr of opamp used is 77dB.now i want to increase the psrr of bandgap to 70dB.how to do that.thanks in advance.

 

[alok_ky]

psrr of bandgap

What PSRR are you talking abt...AC or DC ?

 

[Yun Lin]

psrr of bandgap

You must consider the frequency of noise.

 

[jc2]

Re: psrr of bandgap

you could increase the impedance between the supply node and the output node.

psr=v_supply/v_output

v_output=v_supply*(Rout)/(Rout+R)

v_supply/v_output=(Rout+R)/Rout

R=Resistance between supply node and the output node

then for increasing psr, you could increase R,
You may increase R with a cascode as current mirror or
you can use a pre-regulator.

go to chapter 4 in this book for more information, Voltage reference: from diodes to precision high order bandgap circuits; Gabriel A. Rincón Mora

 

[51906669]

Re: psrr of bandgap

try these:

 

[jonneylu]

psrr of bandgap

think mos near power line

 

[qutang]

psrr of bandgap

I also think jc2's way.and u can try to increase bias current.