Wide dynamic range image sensor pixel cell
AssigneeSmartsens Technology (Cayman) Co., Ltd.
InventorsChen Xu, Yaowu Mo, Zexu Shao, Zhengmin Zhang, Weijian Ma
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Abstract
A pixel cell has a large and small photodiode, transfer transistors, a reset transistor, a dynamic range enhancement capacitor, a capacitor control transistor, a storage capacitor, a storage capacitor control transistor, an amplifier transistor in a source follower configuration and a rolling shutter row select transistor and a readout circuit block. The small and large photodiodes are exposed simultaneously, the large photodiode having a constant exposure while the small photodiode has a chopped exposure and charge transfer to a storage capacitor.
Claims10
An image sensor pixel cell for use in a wide dynamic range image sensor, the image sensor pixel cell comprising:
- a floating drain node which is useful to transform an imaging related charge into an imaging related voltage signal and is directly connected to five components comprising:
- an input gate electrode of an amplifier transistor in a source follower configuration which is useful to couple out the imaging related voltage signal from the floating drain node through a row select transistor to a pixel cell array column line;
- a drain electrode of a first transfer transistor which in turn has a source electrode connected to a first photodiode with low sensitivity to light incident from a scene;
- a source electrode of a double conversion gain control transistor which in turn has a drain electrode connected to a reset transistor and also to a dynamic range enhancement capacitor;
- a drain electrode of a second transfer transistor which in turn has a source electrode connected to a second photodiode with high sensitivity to light incident from a scene in comparison to the first photodiode;
- and
- a drain electrode of a storage gate transfer transistor which in turn has a source electrode connected to the drain electrode of a third transfer transistor whose source electrode is connected to the first photodiode, wherein a storage capacitor is connected between the gate electrode and drain electrode of the third transfer transistor.
An image sensor pixel cell for use in a wide dynamic range image sensor, the image sensor pixel cell comprising:
- a floating drain node which is useful to transform an imaging related charge into an imaging related voltage signal and is directly connected to four components comprising:
- an input gate electrode of an amplifier transistor in a source follower configuration which is useful to couple out the imaging related voltage signal from the floating drain node through a row select transistor to a pixel cell array column line;
- a drain electrode of a first transfer transistor which in turn has a source electrode connected to a first photodiode with high sensitivity to light incident from a scene;
- a source electrode of a double conversion gain control transistor which in turn has a drain electrode connected to a reset transistor and also to a dynamic range enhancement capacitor, wherein the drain electrode of a second transfer transistor is connected to the drain electrode of the double conversion gain transistor and the source of the second transfer transistor is connected to a second photodiode with low sensitivity to light incident from a scene in comparison to the first photodiode;
- and
- a drain electrode of a storage gate transfer transistor which in turn has a source electrode connected to the drain electrode of a third transfer transistor whose source electrode is connected to the second photodiode, wherein a storage capacitor is connected between the gate electrode and drain electrode of the third transfer transistor.
Dependencies are inferred from the claim text.