maxporter
Junior Member level 2
Hi all,
While simulating the output current of a 1uA current mirror I noticed a strange behavior. It’s a straight forward mirror: output is NMOS + cascode NMOS (biased at 950mV), 65nm PDK and 3V devices. Ideal supply and ground. While sweeping the output voltage I noticed an increase in current when Vout approaches Vsupply. Turns out a little bit current (7nA) is flowing in the bulk of the cascode. See screenshot: red is the output, green is Id of the NMOS current mirror (for both I changed the scale) and blue is the current in the bulk of the cascode. What effect am I seeing here? Thanks in advance.
While simulating the output current of a 1uA current mirror I noticed a strange behavior. It’s a straight forward mirror: output is NMOS + cascode NMOS (biased at 950mV), 65nm PDK and 3V devices. Ideal supply and ground. While sweeping the output voltage I noticed an increase in current when Vout approaches Vsupply. Turns out a little bit current (7nA) is flowing in the bulk of the cascode. See screenshot: red is the output, green is Id of the NMOS current mirror (for both I changed the scale) and blue is the current in the bulk of the cascode. What effect am I seeing here? Thanks in advance.