Dynamic-range adjustable pipelined ADC in CMOS image sensor with black-level and offset noise calibration

Abstract

Analysis on the noise caused by dark-current (black level noise) and offset voltages in CMOS image sensor is implemented and a 10 bit pipelined ADC with the function of eliminating the noise is proposed in this paper. Through Connecting a calibration voltage to one input of the SH circuit in Pipeline ADC, the black level noise and offset noise is eliminated. According to the working mode, the input dynamic range of the proposed pipelined ADC can be adjusted through a digital module. As a result, dynamic range is improved by 6.02 dB when the ADC is working on signal-sampling mode. Simulation results show the pipelined ADC has a DNL(Differential Nonlinearity) of +0.41/ − 0.59 LSB, INL(Integral Nonlinearity) of +1.64/ − 1.57 LSB. The SNR is 59.61 dB and ENOB(Effective Number of Bits) is 9.39 bits.