hi every one , i am designinig a BGR for sub-1-v range and low power. I have no clue how to choose the required collector current to drive the PNP device in PTAT loop. Also if anyone can tell me how do i choose the reference current to start with, it will be of great use for me.
normally choose 1uA or 0.5uA for each branch.but you should also trade off the ground noise and power comsumption.
and BJT may choose 1:8 or 1:24 to form common centrid
if the bias current of bjt is too small. the beta of bjt will decrease drasticly.