1.2 V sub-nanoampere A/D converter

CMOS-based integrated biochemical sensors generate photo currents at sub-nanoampere (nA) levels, which present a challenge for digital data acquisition. Proposed is a MOS current-mode analogue-to-digital converter with sub-nA sensitivity. Its inherent low-voltage low-power and small-size capabilities are ideal for portable chemi- or biosensor applications.