High Dynamic Pixel Circuit Based on Variable Integral Capacitance

In the 5T pixel circuit, the integral capacitance is variable by paralleling three NMOS with different threshold voltages. The gate terminal of the integral capacitor is biased at 3.3 V, and the MOS capacitor operates in the depletion zone. It realizes a wide available range of 2 V, a larger full well capacity, and variable conversion gain and noise. Finally, it is concluded that the 5T pixel circuit using this variable integral capacitor has a linearity of more than 84.6% and a dynamic range of 83.9 dB in the low light range of 8 pA-10 pA and the strong light range of 50 pA-500 pA.