Signal processing circuit for solid state image sensor having a structure for suppressing a reset noise
AssigneeNEC Corporation
InventorShiro Tsunai
Life of this patent
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Abstract
A signal processing circuit for a solid state image sensor, includes a charge detection circuit for outputting a signal output from the image sensor, a first inverting amplifier receiving the signal output, and a second inverting amplifier having a source-grounded MOS transistor having a gate connected to receive an output of the first inverting amplifier. A threshold of the MOS transistor is set to be the same as a black reference voltage in the input signal applied to the MOS transistor. Thus, a reset noise included in the signal output from the image sensor is suppressed or removed.
Claims6
A signal processing circuit for a solid state image sensor, the signal processing circuit including a charge detection circuit for outputting a signal output from the image sensor, a first inverting amplifier receiving said signal output, a source follower receiving an output of said first inverting amplifier, a second inverting amplifier receiving an output of said source follower, a switching means connected between an output of said second inverting amplifier and an input of said source follower to construct a feedback type clamp circuit, said second inverting amplifier including a source-grounded first MOS transistor having a gate connected to receive said output of said source follower, an operating voltage being set to be not smaller than a threshold of said first MOS transistor but smaller than an intermediate voltage of an operating voltage range of said second inverting amplifier.
A signal processing circuit for a solid state image sensor, including a charge detection circuit for outputting a signal output from the image sensor, a first inverting amplifier receiving said signal output, and a second inverting amplifier having a source-grounded MOS transistor having a gate connected to receive an output of said first inverting amplifier, a threshold of the MOS transistor being set to be the same as a black reference voltage in the input signal applied to said MOS transistor, so that a reset noise included in said signal output from said image sensor is removed.
Dependencies are inferred from the claim text.