Image sensor floating diffusion boosting by transfer gates

An imaging system, comprising:

• a pixel array including a plurality of groupings, wherein each one of the plurality of groupings includes:
• a plurality of photodiodes, wherein the plurality of photodiodes are coupled to photogenerate image charge in response to incident light;
• a shared floating diffusion coupled to receive the image charge transferred from each one of the plurality of photodiodes;
• and
• a plurality of transfer gates coupled between the plurality of photodiodes and the shared floating diffusion, wherein each one of the plurality of transfer gates is coupled to a corresponding one of the plurality of photodiodes,
• wherein each one of the plurality of transfer gates is coupled to receive a respective one of a plurality of transfer control signals to independently control the transfer of the image charge from the corresponding one of the plurality of photodiodes to the shared floating diffusion, wherein each one of the respective transfer control signals is coupled to be set to one of an ON value, a first OFF value, or a second OFF value,
• wherein a respective one of the plurality of control signals coupled to an active one of the plurality of transfer gates is coupled to be set to the ON value during a transfer operation, and
• wherein respective ones of the plurality of control signals coupled to idle ones of the plurality of transfer gates are coupled to be set to the first OFF value during a reset period prior to the transfer operation, and are coupled to be set to the second OFF value during the transfer operation;
• control circuitry coupled to the pixel array to control operation of the pixel array and to generate the plurality of transfer control signals;
• and
• readout circuitry coupled to the pixel array to readout image data from the plurality of photodiodes.

A pixel, comprising:

• a photodiode coupled to photogenerate image charge in response to incident light;
• a floating diffusion coupled to receive the image charge transferred from the photodiode;
• and
• a transfer gate coupled between the photodiode and the floating diffusion, wherein the transfer gate is coupled to receive transfer control signal to control the transfer of the image charge from the photodiode to the floating diffusion, wherein the transfer control signal is coupled to be set to one of an ON value, a first OFF value, or a second OFF value, wherein the control signal is coupled to be set to the ON value during a transfer operation, wherein the control signal is coupled to be set to the first OFF value during a reset period prior to the transfer operation, and wherein the control signal is coupled to be set to the second OFF value when the pixel is in an inactive row.