Matrix image sensor providing bidirectional charge transfer with asymmetric gates

Abstract

In the field of image sensors, more particularly time-delay integration linear sensors or TDI sensors, a sensor comprises rows of photodiodes alternating with rows of gates adjacent to the photodiodes. The gates are asymmetric, adjacent on one side to a photodiode and having, on the other side, narrow gate fingers extending toward another photodiode. Owing to their very narrow width, the fingers endow the transfer of charges with a directionality. Between two successive photodiodes there are two gates, the two being adjacent to the two photodiodes, the first having its narrow fingers turned toward the first photodiode, the second having its narrow fingers turned toward the second photodiode. The direction of transfer of the charges in the sensor may be chosen by neutralizing either the first gate or the second gate, the other gate receiving alternating potentials allowing the transfer of charges from one photodiode to the other.