CMOS IMAGER WITH WIDE DYNAMIC RANGE PIXEL

摘要

A light sensor is provided in the active pixel sensor cell for sensing incident radiation. The voltage corresponding to a photon-generated charge in the cell is stored on a storage node via a sample-and-hold capacitor. The signal is read via a readout source-follower (RSF) transistor. The RSF drain is connected to the row select switch while its drain is connected to the output node on the column output bus. This configuration couples the storage node to the gate-source capacitance of the RSF transistor, allowing the voltage on the storage node to increase proportionally to the increase in voltage on the readout node when the row select is closed and enabling the drain current to flow through the RSF to the column output bus.