A novel current-mode multi-channel integrating ADC

A novel current-mode multi-channel ADC has been designed, fabricated, and characterized in a 0.5-lm bulk CMOS process. The ADC utilizes a Wilkinson architecture with current-mode comparators and is capable of supporting multiple channels with an input current range of 10-150 μA. The main blocks in the ADC include a current ramp generator with active current mirrors, multiple current comparators, and a 12-bit Gray code counter. A novel architecture Gray code counter supports high frequency counting. For sampling rates up to 10 kHz, measurement results are presented including integral nonlinearity and differential nonlinearity. A per-channel power consumption of less than 2 mW using a Wilkinson architecture with 4 channels was observed. This work represents the first published current-mode, multi-channel Wilkinson ADC.