How to improve PSRR of a BGR?

[tsai_chin_wei]

Hi,

I am designing a BGR and PSRR simulations confuse me.

I simulate PSRR+ by adding a dc source(amplitude=5V) and a ac source(amplitude=5V) at VDD and then PSRR+ is about -70dB.

Similarly, I simulate PSRR- by adding a dc source(amplitude=0V) and a ac source(amplitude=5V) at VSS and then PSRR- is about 0dB.

spice commands:

VDD VDD gnd DC=5 AC=1

VSS VSS gnd DC=0

.............for PSRR+ simulation

VDD VDD gnd DC=5

VSS VSS gnd DC=0 AC=1

.............for PSRR- simulation


So, I don't know if the simulations are right. If the simulations are all right, how to

improve PSRR- of the BGR?

 

[ebalboni]

BGR PSRR simulations

You sim is correct. The only way to improve PSRR- is to use a differential output BGR.

 

[mists]

Re: BGR PSRR simulations

You sim is correct. The only way to improve PSRR- is to use a differential output BGR.

may you give more information of "differential output BGR" thanks!

 

[gevy]

Re: BGR PSRR simulations

Second way to improve PSRR is to use bandgap voltage reference with amplifier.

 

[leo_o2]

BGR PSRR simulations

I think PSRR- = 0dB is OK, because you are designing a reference voltage related to ground. That means the reference will follow ground voltage if PSRR-=0dB. If you really want to increase it, you must design the reference voltage related to another voltage potential.