Hi, Mayank
This comparator is used in an feedback loop to form an relaxation oscillator and I use the inverter chain here just to avoid metastability. And I don't think its contribution to the overall delay is significant. Here I only want to increase the speed of the open-loop opamp.
I searched "cross coupled Level-Shifter", but I did not get what I desired. Could you provide more details?
After posting, I randomly swept the transistors' size and got a much better result. And I found that the result is even worse if I use PMOS input diff-pair. But to be frank, I still don't know exactly the mechanism about that "overshooting". :-/
To BOE,
You are right, but I believe there is systematic delay for the comparator, not just common intrinsic delay, since 2ns is too large for 0.18um devices.
To loose-electron,
I don't know what "conventional approaches" are, can you provide me with information on continously-working fast comparator?
Thank you for your comment.