Partial pixel oversampling for high dynamic range imaging

An imaging device, comprising:

• a pixel-circuit comprising a photodetector, the photodetector configured to accumulate electrical charge in response to incident light;
• and
• a readout circuit, configured to:
• perform a series of iterations, each iteration comprising (i) accumulating an electrical charge in the photodetector during an integration time, (ii) transferring a portion of the electrical charge accumulated in the photodetector to a floating less than all the diffusion, the portion being electrical charge accumulated in the photodetector, and (iii) coupling a voltage of the floating diffusion to a storage capacitance;
• subsequently, in a final iteration, transfer a remaining electrical charge from the photodetector;
• and
• derive an output digital value, indicative of a total energy of the light incident on the photodetector over the series of iterations and the final iteration, from the voltage on the storage capacitance and from the remaining electrical charge transferred in the final iteration,
• wherein the readout circuit is configured to:
• transfer the electrical charge from the photodetector to the storage capacitance for the iterations in the series, and derive a first interim digital value from the voltage on the storage capacitance;
• transfer the electrical charge from the photodetector to the storage capacitance separately for the final iteration, and derive a second interim digital value from the voltage on the storage capacitance;
• and
• derive the output digital value from the first and second interim digital values.

An imaging method, comprising:

• accumulating electrical charge in a photodetector in response to incident light;
• performing a series of iterations, each iteration comprising (i) accumulating an electrical charge in the photodetector during an integration time, (ii) transferring a portion of the electrical charge accumulated in the photodetector to a floating diffusion, the portion being less than all the electrical charge accumulated in the photodetector, and (iii) coupling a voltage of the floating diffusion to a storage capacitance;
• subsequently, in a final iteration, transferring a remaining electrical charge from the photodetector;
• and
• deriving an output digital value, indicative of a total energy of the light incident on the photodetector over the series of iterations and the final iteration, from the voltage on the storage capacitance and from the remaining electrical charge transferred in the final iteration,
• wherein coupling the voltage of the floating diffusion to the storage capacitance is performed via a variable capacitance, and comprising varying a capacitance of the variable capacitance across the series of iterations, thereby coupling to the storage capacitance a weighted average of voltages of the floating diffusion from the iterations.