caosl
Advanced Member level 4
hi, all:
I have designed a bandgap reference,the structure which i adopted is traditional,namely, the opamp's output is connected to two pmos's gate to adjusted the current. Now, the output voltage is change 1.2mv in the range of -40-->125,the startup circuit is ok. The only problem is the overshoot and undershoot is too large(200mv)when add a unit step(1V) on supply voltage,but the static accurancy(line regulation) is very well(20uV/V).Addtionally,the opamp's unity gain bandwidth is 5M,DC gain is 80dB, phase margin is large than 60.In my opinion, this opamp's performance is meet to bandgap reference's requirement.Please help me to reduce this overshoot(undershoot). Any advice is welcome.Thanks a lot!
I have designed a bandgap reference,the structure which i adopted is traditional,namely, the opamp's output is connected to two pmos's gate to adjusted the current. Now, the output voltage is change 1.2mv in the range of -40-->125,the startup circuit is ok. The only problem is the overshoot and undershoot is too large(200mv)when add a unit step(1V) on supply voltage,but the static accurancy(line regulation) is very well(20uV/V).Addtionally,the opamp's unity gain bandwidth is 5M,DC gain is 80dB, phase margin is large than 60.In my opinion, this opamp's performance is meet to bandgap reference's requirement.Please help me to reduce this overshoot(undershoot). Any advice is welcome.Thanks a lot!