Image sensor with reduced column fixed pattern noise

An image sensor, comprising:

• an image sensor pixel;
• a pixel output line coupled to the image sensor pixel;
• a current source transistor coupled to the pixel output line, the current source transistor having a threshold voltage;
• a cascode transistor coupled between the pixel output line and the current source transistor;
• and
• a threshold voltage mitigation circuit coupled to the current source transistor and configured to produce an output current on the pixel output line that is independent of the threshold voltage of the current source transistor, wherein the threshold voltage mitigation circuit is configured to receive a global control voltage.

An image sensor, comprising:

• an image sensor pixel;
• a column line coupled to the image sensor pixel;
• a current source transistor coupled to the column line, the current source transistor having a threshold voltage;
• and
• a threshold voltage mitigation circuit coupled to the current source transistor, wherein the threshold voltage mitigation circuit is operable in:
• a calibration phase during which the threshold voltage mitigation circuit provides a reference current to the current source transistor;
• a control phase during which a global control signal is provided to the current source transistor;
• and
• an output enable phase during which the current source transistor sinks an output current that does not vary as a function of the threshold voltage.