A 256 × 256 CMOS image sensor with differential readout and data converter circuits

Summary In this paper, a 256 × 256 CMOS image sensor is introduced in which the pixel signals are read and converted into digital data in a completely differential mode. This technique helps to obtain pixel signals with higher linearity and accuracy compared with conventional methods. Improving the linearity and accuracy of the image sensor has a direct impact on increasing the quality of the generated images. The simulation results of the proposed pixel readout circuit show that the THD, SINAD, SNR, and SFDR are 0.45%, 47 dB, 66 dB, and 46 dB, respectively. The voltage gain of the proposed readout circuit is about 1, causing it to read the photodetector signals more accurately than the conventional methods. A full differential single‐slope ADC with a working frequency of 50 Mhz has the task of converting the pixel signal to 10 bits of digital data. The total power consumption of a column of sensors is about 80 μW. All the circuits are designed and implemented using 0.18‐μm CMOS technology in Virtuoso and simulated by the SPECTRE. In this paper, a new CIS was proposed that can read out the pixel signals and convert them to digital in differential mode. This technique helps to read and convert pixel signals with more linearity and higher accuracy compared with the conventional way.