WAVELENGTH SELECTIVE RADIATION SENSOR

There may be provided a radiation sensor, that may include multiple semiconductor regions that form a sensing PN junction and a draining PN junction that is located below the sensing PN junction; a bias circuit that is configured to (i) bias the sensing PN junction to maintain a sensing PN junction depletion region of a fixed size during a first sensing period and during a second sensing period, and (i) bias the draining PN junction to form a draining PN junction depletion region of a first size during the first sensing period and of a second size during the second sensing period; and an output circuit that is configured to generate a first output signal that represent sensed radiation out of radiation that impinged on the radiation sensor during the first sensing period, and to generate a second output signal that represent sensed radiation out of radiation impinged on the radiation sensor during the second sensing period.