High dynamic range imager circuit and method for reading high dynamic range image

A high dynamic range image sensor device, comprising:

• a photosensor unit for receiving a light signal to generate and accumulate photo-generated charges;
• a floating diffusion node for storing floating diffusion charges;
• a transfer gate for coupling the photosensor unit to the floating diffusion node to transfer at least portion of the photo-generated charges to the floating diffusion node as the floating diffusion charges;
• at least one variable capacitor having a capacitance which is adjustable according to an adjustment voltage;
• and
• a dual conversion gain transistor coupled between the floating diffusion node and the variable capacitor, for receiving a conversion gain signal and electrically coupling the floating diffusion node to the variable capacitor in response to the conversion gain signal, for adjusting a gain of reading the floating diffusion charges.

A high dynamic range imager apparatus, comprising:

• an image sensor device array, including:
• a plurality of image sensor devices arranged in a plurality of rows and columns, each of the image sensor devices including:
• a photosensor unit for receiving a light signal to generate and accumulate photo-generated charges;
• a floating diffusion node for storing floating diffusion charges;
• a transfer gate for coupling the photosensor unit to the floating diffusion node to transfer at least portion of the photo-generated charges to the floating diffusion node as the floating diffusion charges;
• at least one variable capacitor having a capacitance which is adjustable according to an adjustment voltage;
• and
• a dual conversion gain transistor coupled between the floating diffusion node and the variable capacitor, for receiving a conversion gain signal and electrically coupling the floating diffusion node to the variable capacitor in response to the conversion gain signal, for adjusting a gain of reading the floating diffusion charges;
• a signal reading circuit coupled to the image sensor device, for converting the floating diffusion charges to a signal which indicates a pixel image sensed by the image sensor device;
• a digital-to-analog conversion circuit coupled to the signal reading circuit, for converting the signal indicating the pixel image sensed by the image sensor device to a digital image signal;
• and
• an image process circuit coupled to the digital-to-analog conversion circuit, for processing the digital image signal.

A method of reading a high dynamic range image, comprising:

• receiving a light signal to generate and accumulate photo-generated charges;
• transferring at least portion of the photo-generated charges to a floating diffusion node as floating diffusion charges according to a transfer signal;
• electrically coupling the floating diffusion node to a variable capacitor according to a conversion gain signal, for adjusting a gain of reading the floating diffusion charges, wherein the variable capacitor has a capacitance which is adjustable according to an adjustment voltage;
• and
• reading the floating diffusion charges as a first signal, which indicates a sensed pixel image.