A Wide Dynamic Range CMOS Image Sensor With Multiple Exposure-Time Signal Outputs and 12-bit Column-Parallel Cyclic A/D Converters

摘要

A wide dynamic range CMOS image sensor with a burst readout multiple exposure method is proposed. In this method, maximally four different exposure-time signals are read out in one frame. To achieve the high-speed readout, a compact cyclic analog-to-digital converter (ADC) with noise canceling function is proposed and arrays of the cyclic ADCs are integrated at the column. A prototype wide dynamic range CMOS image sensor has been developed with 0.25-μm 1-poly 4-metal CMOS image sensor technology. The dynamic range is expanded maximally by a factor of 1791 compared to the case of single exposure. The dynamic range is measured to be 19.8 bit or 119 dB. The 12-bit ADC integrated at the column of the CMOS image sensor has DNL of +0.2/-0.8 LSB.