LDO- pass device driver

[jutek]

hello

i am trying to choose a proper pass device size.

I am using an ibm 0.13um model.

I simulate lowest input voltage and max load current conditions. i want it to work in the saturation error.


When i use W=10m L=0.5u Vgs should be -0.62V to give me 100mA

It means Vg potential is +0.68V I have also one severe demand. Pass device leakage current should be less than 5uA which means voltage gain should be very close to input voltage

The highest input voltage is 3.3V.

My question is about opamp's output which drives pass device. How to assure this voltage swing?

regards

 

[paulux]

I guess your highest voltage swing of your amp should be closer than Vdd-Vthp(threshold voltage of your P pass device), thus you can minimize the leakage current.