Hi everyone, I'm doing a project of two stage op amp, differential input as the first stage and common source as the second stage. As it is assumed a 5k resistor on the load, I need an output stage. The project spec requires that the output swing to be within 0.5v of upper and lower rail. I was planning to use a source follower but it doesn't work, because the source follower is gate input and source output and in this case, there is a minimum Vdsat+Vth voltage difference either on upper or lower rail. I'm a little bit stuck on this problem. Can someone give me some advice? Thanks!