Patent ID: 8730358

Claim:
An image sensor, comprising: a photoelectric conversion unit; a sensing node; a transfer switch that electrically connects the photoelectric conversion unit to the sensing node; an output transistor that outputs signals in response to signals on the sensing node; a reset switch that electrically connects a source of reference voltage to the sensing node; and a first circuit configured to: sample a first signal from the output transistor when the reset switch is in a triode region, sample a second signal from the output transistor when the reset switch is non-conducting and the transfer switch is in a triode region, sample a third signal from the output transistor after the second signal when the reset switch and the transfer switch are both non-conducting, sample a fourth signal from the output transistor after the third signal when the reset switch is in a triode region, sample a fifth signal from the output transistor after the third signal when the transfer switch remains non-conducting since the third signal and the reset switch is non-conducting, sample a sixth signal from the output transistor after the fifth signal when the transfer switch is in triode region and the reset switch remains non-conducting since the fifth signal, form a noise signal from the first, second and third signals with a first set of signed scaling factors, form a normalized light response signal from the fourth, fifth and sixth signals with a second set of signed scaling factors, wherein the first set of scaling factors and the second set of signed scaling factors are essentially equal.