Comparator in Analog To Digital Convertor

Thread Starter

Majid Vatan Parast

Joined Dec 6, 2014
Hello everybody
I want to design a charge redistribution SAR ADC , but my comparator does not work for negative input , it does not compare zero and negative voltages correctly , I have got the comparator circuit from a paper . what should I do?
Please help me :(:(:(


Joined Oct 21, 2014
Thanks for the information.

Your comparator is not able to compare 0V with negative voltages. You have NMOS transistors as input transistors. For example when:

INP = 0V
INN = -1V

both transistors are off. You need PMOS as input transistors.