Patent ID: 6677996
Filing Date: 2004-01-13
Classification: H01L,H04N

Abstract:
An active pixel sensor circuit which produces a current component mathematically related to photon bombardment, said sensor circuit comprising:a light accumulation circuit which produces a voltage component mathematically related to a cumulative amount of light which has fallen on a light sensitive component within the light accumulation circuit; a variable DC power source capable of providing at least two voltage potentials, a first potential in the range of zero to 0.5 volts, and a second potential in the range of 1.5 to 6 volts; a selecting transistor comprising a first terminal, a second terminal and a gate, the second terminal of the selecting transistor being connected to the variable DC power source; a current regulating transistor comprising a first terminal a second terminal, and a gate, the gate operatively connected to the light accumulation circuit, the second terminal operatively connected to the first terminal of the selecting transistor, and the first terminal operatively connected to a current bus; a current mirror transistor comprising a source, a drain, and a gate; a current source operatively connected to the source of the current mirror transistor; a terminal of 0 to 0.5 volt potential operatively connected to the drain of the current mirror transistor; a conductive link operatively connecting the drain and the gate of the current mirror transistor; the sate of the current mirror transistor is operatively connected to the row selection bus; and a row selection bus operatively connecting the current mirror circuit to the gate of the selecting transistor, the row selection bus including a buffer between the gate of the selecting transistor and the gate of the current mirror transistor.