Wide Swing Cascode Current Mirror Biasing Difficulties
you don't have a bias, therefore an incomplete current mirror, so electrically it will act as a class A stage with a ccs

Stick a resistor in where Ibias would be so you can bias the bottom fets

Here is another example:



I recommend you look at this guy's page, since you are learning the circuit:
http://cmosedu.com/jbaker/courses/ee420L/s17/students/garrod/Lab%209/Lab%209.htm