A salient integration mode active pixel sensor. The active pixel sensor
includes an amplify/compare transistor which has a threshold voltage. The
amplify/compare transistor couples an input of the amplify/compare
transistor to an output of the amplify/compare transistor when the input
of the amplify/compare transistor exceeds the threshold voltage. A
photo-diode generates a signal voltage which has a voltage level dependent
upon the intensity of light received by the photo-diode. The signal
voltage is coupled to the input of the amplify/compare transistor. A reset
element couples a reset line to the photo-diode and discharges the
photo-diode when the reset line is active. A coupling capacitor for
couples a select line to the input of the amplify/compare transistor. The
select line causes the input to the amplify/compare transistor to exceed
the threshold voltage and thereby couple the signal voltage to the output
of the amplify/compare transistor. The amplify/compare transistor can be
an N-type MOSFET and the reset transistor can be an N-type MOSFET.
Further, a back gate of the amplify/compare transistor is generally
connected to a circuit ground.