jutek
Full Member level 4
hello
I need a circuit which will introduce an internal zero in LDO's frequency response. I will also use an external capacitor but i could use lower esr then.
I have found one solution, but it makes problems for me. It's presented in
A robust frequency compensation scheme for LDO regulators
Chava, C.K. Silva-Martinez, J.
Analog & Mixed Signal Center, Texas A&M Univ., College Station, TX, USA
Current IB should be very low (max. 0.5uA) to not affect LDO's output voltage.
But the pole which this ciurcuit introduces is gm1/C1. Low IB means low gm1 and low frequency pole, so the compensation doesn't work.
I need something to increase gm without increasing IB current.
In the b) picture authors presented solution which should help.
Unfortunately in my design i use low vdd (1.3V) and vout equals to 0.8 so the input pair won't work properly.
How can i increase gm1 transconductance and increase input's resistance?
regards
I need a circuit which will introduce an internal zero in LDO's frequency response. I will also use an external capacitor but i could use lower esr then.
I have found one solution, but it makes problems for me. It's presented in
A robust frequency compensation scheme for LDO regulators
Chava, C.K. Silva-Martinez, J.
Analog & Mixed Signal Center, Texas A&M Univ., College Station, TX, USA
Current IB should be very low (max. 0.5uA) to not affect LDO's output voltage.
But the pole which this ciurcuit introduces is gm1/C1. Low IB means low gm1 and low frequency pole, so the compensation doesn't work.
I need something to increase gm without increasing IB current.
In the b) picture authors presented solution which should help.
Unfortunately in my design i use low vdd (1.3V) and vout equals to 0.8 so the input pair won't work properly.
How can i increase gm1 transconductance and increase input's resistance?
regards