A 0.6V CMOS Image Sensor with in-pixel biphasic current driver for biomedical application

A 0.6V pulse frequency modulation (PFM) CMOS Image Sensor (CIS) array with in-pixel biphasic current pulse driver is presented in this paper. It achieves a photon-to-biphasic current conversion for biomedical applications like artificial 2-D vision recovery. The photon-to-biphasic-current conversion gain, the biphasic pulse width, polarity, and output rate are all tunable depends on applications and environments. A 32×32 pixel array with 30×30 um² pixel size has been designed and fabricated in 0.18um CMOS technology providing the fill factor of 24.5%. Measurement results show a 0.63Hz/lux conversion gain of PFM sensor within 25hz~5kHz output with power consumption as 2uW~55uW depends on illumination. The maximum driving capability of biphasic neural stimulation current pulse is ±20μA with a 10kΩ electrode model.