MOSFET Differential Pair (Analysis)

Hello,

I am testing a MOSFET differential pair with resisitive load and as well as Active (MOS) loads. In DC simulation with resistors as load I can calculate the Differential Output voltages and Currents but with MOS loads I also want to calculate the differential output (vout1 vout2) which sis not showing a proper waveform, I am biasing the MOS loads through extra transistor. Could anyone tell me what could be the reason behind this?.

Also, I want to run the small signal AC simulations to calculate the differential gain, Common mode gain and CMRR. Any hints on how should I connect sources with Vin1 and Vin2 ?

I read about differential amplifiers from CMOS circuit design 3rd Edition by R. jacob and Design of Analog MOS Integrated circuits by behzad razavi, but still it is un clear for the ac analysis.

Thanks

P.S: I am working with cadence design environment.

Pls. show your schematic & testbench which did not result in a proper waveform, together with your current Vin1 & Vin2 connection.