Hdr skimming photodiode with true led flicker mitigation

Abstract

Apparatuses and methods for a skimming photodiode with high dynamic range (HDR) and reduced Light Emitting Diode (LED) flicker in imaging system are disclosed herein. A voltage generator provides a transfer gate voltage to a transfer transistor. The transfer gate voltage is a voltage selected one of a transfer-on, a transfer-off, and a skimming voltage. The transfer transistor transfers charges generated on a Complementary Metal-Oxide-Semiconductor (CMOS) photodiode (PD) to a floating diffusion (FD). The voltage on transfer gate controls the amount of the charges that can be transferred from the PD to the FD. A reset transistor precharges the PD and FD to an AVDD. A first enable transistor controls the amount of charges transferred from the FD to a first capacitor. A second enable transistor controls the amount of charges transferred from the FD to a second capacitor. The first and second enable transistors receive their individual periodical control pulses once activated. Charges collected on the first and second capacitors are transferred to the FD. A source follower transistor amplifies voltage appeared on the FD. A row select transistor sends the amplified voltage to the bitline for signal readout.