Bandgap Refernce Design

[dkace]

Hi all,

I have a Brokaw Bandgap with a negative feedback to control the currents.

I have a small issue understanding how a small difference on the voltage of node 1 can be negated with this feedback.

I have an equation cluster but it seems I am missing something, or I am working the wrong way.

Can anyone guide me through this?

Thanks,

D.

 

[wjlzhx]

I think it has two feedback ,0ne is positive and another is negetive ,Q2 and Q4 is negetive ,PT332 Q4 Q0 is positive,when negetive > positive it is stable

 

[dkace]

There is only one feedback, and I think is negative.

The issue is to keep the voltage at the gate of the TP332 as the voltage at the Drain of the mirror generator.

This stage is a single fet amplifier. Then the output stage is a BiCMOS output with the BJT base controlled by the buffered output (Vout).

I want to verify my equation derived by the hybrid model.

Can anyone assist?

Thanks,

D.

 

[pmr9]

Whats your equation?

 

[zhuleiyacht]

I disagree on your comment:"There is only one feedback, and I think is negative.". I also think it has 2 loops ,one is positive, another is negative. if your RRR0-8 is too small around 1/gm same order. the positive loop may conduct it unstable