An image sensor includes pixels formed on a semiconductor substrate. Each pixel
includes a photoactive region in the semiconductor substrate, a sense node, and
a power supply node. A first electrode is disposed near a surface of the semiconductor
substrate. A bias signal on the first electrode sets a potential in a region of
the semiconductor substrate between the photoactive region and the sense node.
A second electrode is disposed near the surface of the semiconductor substrate.
A bias signal on the second electrode sets a potential in a region of the semiconductor
substrate between the photoactive region and the power supply node. The image sensor
includes a controller that causes bias signals to be provided to the electrodes
so that photocharges generated in the photoactive region are accumulated in the
photoactive region during a pixel integration period, the accumulated photocharges
are transferred to the sense node during a charge transfer period, and photocharges
generated in the photoactive region are transferred to the power supply node during
a third period without passing through the sense node. The imager can operate at
high shutter speeds with simultaneous integration of pixels in the array. High
quality images can be produced free from motion artifacts. High quantum efficiency,
good blooming control, low dark current, low noise and low image lag can be obtained.