A single-slope based low-noise ADC with input-signal-dependent multiple sampling scheme for CMOS image sensors

This paper presents a multiple-sampling technique using a Single-Slope ADC (SSADC) for low-noise CMOS image sensors. In the proposed technique, the number of sampling is controlled depending on an input signal to effectively reduce the noise of a readout circuit at dark-light illumination. An example of circuit implementation is illustrated. The simulation results show the increase of number of sampling and the reduction of the readout circuit noise at a small input signal. The improvement of SNR is 22.8dB.