Current Sensing-Assisted Active Pixel Sensor for High-Speed CMOS Image Sensors

In this paper, we describe an active pixel CMOS image sensor that employs a current-sensing readout circuit. The readout uses a column-level current-sensing amplifier with negative feedback to increase current driving capability, which gives significantly faster settling time. A prototype 128 × 3 pixel sensor with a current gain of 10 was fabricated using standard 0.3-μm CMOS technology and demonstrated a reduction in settling time by a factor of 14 for both negative and positive voltage swings of the output node. The power consumption of the column-level readout amplifier is 110 μW.