14.3-bit extended counting ADC with built-in binning function for medical X-ray CMOS imagers

Abstract

Proposed is a 14.3-bit extended counting analogue-to-digital converter (ADC) with built-in binning function for medical X-ray CMOS imagers. To reduce the area and improve the image resolution simultaneously, the proposed ADC internally performs the analogue binning operation without a charge amplifier. The ADC also uses an extended input range to realise true 14-bit dynamic range when applying the digital correlated double sampling technique. The proposed ADC was fabricated using a 0.35 mu m CMOS process and the measured differential and integral nonlinearities of the 14.3-bit ADC are +0.97/-0.79 and +2.79/-1.70 LSB, respectively.