Patent ID: 10848703

Abstract:
A CMOS image sensor comprises an array of pixels. A column of the pixel array is coupled to a readout column. The readout column is couple to a readout circuitry (RC) that reads out image data from the pixel array. The RC comprises two sampling switches which are coupled to a 2-column successive approximation register (SAR) analog-to-digital converter (ADC). The 2-column SAR ADC comprises a differential comparator, a local SAR control, and two digital-to-analog converters (DACs). The two sampling switches are coupled between two readout columns and two inputs of the differential comparator, respectively. An image readout method reads two pixels with three conversions through the RC. The RC is operated by the local SAR control to set the two DACs based on comparator output, and upon which a reset digital value is obtained and stored. An overall reduced algorithm calculation is achieved herein.