How to keep Bandgap output voltage as constant ?

[pillar_chen]

I couldn't understand whay you write, The BGR will generate output voltage independable on the VDD. The change is small with VDD change.

 

[pillar_chen]

May be your OTA function failed

 

[derknand]

The BGR I designed also has bad stability.The output votage changed with the variety of VDD.
The OA is correct and good performance, and I also used cascode. All transistors work in saturation.
When VDD changed between 8v to 18v,the output changed about 20mv.I don't know why.

I hope someone can tell me how to improve the PSRR!Thand u very much!!!

 

[sorata]

The key point to design a low temp. drift bandgap reference is the performance of opamp,i think possibly the op didn't work well over your interested power supply range . so , high gain , enough phase margin, high psrr ,small bandwidth of opamp is needed for small TC of output over temp. range &power supply range.

br,
sorata

 

[yaxazaa]

First you need design good PSRR circuit,
Second you need buffer and fliter the VBG node.

 

[icpilipala]

just like yaxazaa said
if AMP is good ,then try put a cap at the output

 

[xerxer]

your current is too large ~~~~~
i met the trouble .smaller your current in bandgap regeration branch.