What is Replica bias circuit？

What is Replica bias circuit?
Why do we use replica bias circuit?
When do we use replica bias circuit?

The replica bias circuit is a bias circuit which has the same strcture as the biased circuit.
The replica bias circuit can generate the bias value which can trace the variation of temperature, process ....
When the biased circuit is very sensitive to these variation of its bias values.

反馈用呗

同问，能举个例子吗