Patent ID: 7573017

Claim:
An active pixel sensor, comprising: a first transistor for amplifying voltage generated in response to light at an integration node N; a second transistor functioning as a selecting transistor, the second transistor selecting a specific pixel from a pixel array; a third transistor resetting voltage of the integration node N to voltage supplied from VDD during a reset period; a fourth transistor functioning as a photogate, the fourth transistor connecting a photogate capacitance to the integration node N and thus increasing a dynamic range when the voltage of the integration node N is VDD-Vth (photogate: fourth transistor); a fifth transistor functioning as a logarithmic transistor, the fifth transistor generating a signal voltage in a logarithmic response to light when the voltage of the integration node N is logarithmic bias voltage−Vth (logarithmic TRansistor (TR): fifth transistor); and a photodiode, for converting photons into electron pairs in a depletion layer, and then causing signal charges to be accumulated when light is incident from outside.