Method and apparatus providing multiple exposure high dynamic range sensor

An apparatus comprising:

• a plurality of storage elements to store first respective reset and signal voltages as intermediate reset and signal voltages, the first reset and signal voltages corresponding to a first integration time for a pixel;
• a circuit for providing an overwrite indication signal having a first value if the difference between the first reset and signal voltages corresponds to a saturation condition of the pixel and a second value if the difference between the first reset and signal voltages does not correspond to the saturation condition;
• and
• a circuit for overwriting the first reset and signal voltages with second reset and signal voltages as the intermediate reset and signal voltages if the overwrite indication signal has the first value, the second reset and signal voltages corresponding to a second integration time for the pixel that is less than the first integration time, wherein the circuit for providing the output signal comprises:
• a low gain module coupled to the plurality of storage elements to amplify the intermediate reset and signal voltages using a first gain to provide a low gain intermediate differential signal;
• a high gain module coupled to the plurality of storage elements to amplify the intermediate reset and signal voltages using a second gain that is greater than the first gain to provide a high gain intermediate differential signal;
• and
• a multiplexer to provide a qualifying intermediate signal, wherein the qualifying intermediate signal is the low gain intermediate differential signal if the high gain intermediate differential signal is greater than a reference threshold, and wherein the qualifying intermediate signal is the high gain intermediate differential signal if the high gain intermediate differential signal is less than the reference threshold.

An imager comprising:

• a pixel array including a pixel that provides electrons based on photons incident on the pixel;
• and
• a module coupled to the pixel array, said module comprising:
• a plurality of storage elements to store first respective reset and signal voltages as intermediate reset and signal voltages, the first reset and signal voltages corresponding to a first integration time for a pixel;
• a comparator to provide an overwrite indication signal having a first value if the difference between the first reset and signal voltages corresponds to a saturation condition of the pixel and a second value if the difference between the first reset and signal voltages does not correspond to the saturation condition;
• logic to overwrite the first reset and signal voltages with second reset and signal voltages as the intermediate reset and signal voltages if the overwrite indication signal has the first value, the second reset and signal voltages corresponding to a second integration time for the pixel that is less than the first integration time;
• a low gain module coupled to the plurality of storage elements to amplify the intermediate reset and signal voltages using a first gain to provide a low gain intermediate differential signal;
• a high gain module coupled to the plurality of storage elements to amplify the intermediate reset and signal voltages using a second gain that is greater than the first gain to provide a high gain intermediate differential signal;
• and
• a multiplexer to provide a qualifying intermediate signal, wherein the qualifying intermediate signal is the low gain intermediate differential signal if the high gain intermediate differential signal is greater than a reference threshold, and wherein the qualifying intermediate signal is the high gain intermediate differential signal if the high gain intermediate differential signal is less than the reference threshold.

A method comprising:

• comparing a difference between first reset and signal voltages corresponding to a first integration time for a pixel and a saturation threshold corresponding to a saturation condition of the pixel;
• providing intermediate reset and signal voltages for the pixel, wherein the intermediate reset and signal voltages are the first reset and signal voltages if the difference between the first reset and signal voltages is less than the saturation threshold, and wherein the intermediate reset and signal voltages are second reset and signal voltages corresponding to a second integration time for the pixel that is less than the first integration time if the difference between the first reset and signal voltages is greater than the saturation threshold;
• comparing a difference between third reset and signal voltages corresponding to a third integration time for the pixel that is greater than the first integration time and the saturation threshold;
• and
• providing an output signal for the pixel, wherein the output signal is based on the intermediate reset and signal voltages if the difference between the third reset and signal voltages is greater than the saturation threshold, and wherein the output signal is based on the third reset and signal voltages if the difference between the third reset and signal voltages is less than the saturation threshold.

A method comprising:

• storing a first reset voltage and a first signal voltage for a pixel corresponding to a first integration time t1 using a first plurality of storage elements;
• storing a second reset voltage as an intermediate reset voltage and a second signal voltage as an intermediate signal voltage for the pixel using a second plurality of storage elements, wherein the second reset and signal voltages correspond to a second integration time t2 that is less than the first integration time t1;
• overwriting the second reset voltage with a third reset voltage as the intermediate reset voltage and the second signal voltage with a third signal voltage as the intermediate signal voltage for the pixel if the difference between the second reset and signal voltages corresponds to a saturation condition of the pixel, wherein the third reset and signal voltages correspond to a third integration time t3 that is less than the second integration time t2;
• and
• providing an output signal, wherein the output signal is based on the intermediate reset and signal voltages if the difference between the first reset and signal voltages corresponds to the saturation condition of the pixel, and wherein the output signal is based on the first reset and signal voltages if the difference between the first reset and signal voltages does not correspond to the saturation condition of the pixel.

A method comprising:

• storing a first reset voltage and a first signal voltage for each pixel of a plurality of pixels that represent a row of an image using respective storage elements of a first plurality of storage elements, the respective first reset and signal voltages corresponding to a first integration time t3 for the pixels;
• storing a second reset voltage and a second signal voltage for each pixel of the plurality of pixels using respective storage elements of a second plurality of storage elements, the respective second reset and signal voltages corresponding to a second integration time t2, wherein t1>t2;
• comparing a difference between the second reset and signal voltages for each pixel and a first saturation threshold;
• overwriting the second reset voltage and the second signal voltage with a third reset voltage and a third signal voltage for each pixel for which the difference between the second reset and signal voltages is greater than the first saturation threshold, the respective third reset and signal voltages corresponding to a third integration time t3, wherein t2>t3;
• providing a first signal for each pixel based on the voltages stored using the respective storage elements of the first plurality of storage elements;
• providing an intermediate signal for each pixel based on the voltages stored using the respective storage elements of the second plurality of storage elements;
• comparing the first signal and a second saturation threshold;
• and
• providing an output signal for each pixel, wherein the output signal for a pixel of the plurality of pixels is the respective intermediate-signal if the first signal is greater than the second saturation threshold, and wherein the output signal for the pixel is the respective first signal if the first signal is less than the second saturation threshold.

A sensor readout module comprising:

• a sample module including:
• a first plurality of storage elements to store first respective reset and signal voltages as intermediate reset and signal voltages, the first reset and signal voltages corresponding to a first integration time for a pixel,
• a circuit for providing an overwrite indication signal having a first value if the difference between the first reset and signal voltages corresponds to a saturation condition of the pixel and a second value if the difference between the first reset and signal voltages does not correspond to the saturation condition,
• a circuit for overwriting the first reset and signal voltages with second reset and signal voltages as the intermediate reset and signal voltages if the overwrite indication signal has the first value, the second reset and signal voltages corresponding to a second integration time for the pixel that is less than the first integration time, and
• a second plurality of storage elements to store third respective reset and signal voltages corresponding to a third integration time for the pixel, wherein the third integration time is greater than the first integration time;
• and
• a circuit for providing an output signal for the pixel, wherein the output signal is based on the intermediate reset and signal voltages if a difference between the third reset and signal voltages corresponds to the saturation condition, and wherein the output signal is based on the third reset and signal voltages if the difference between the third reset and signal voltages does not correspond to the saturation condition.

An imager comprising:

• a pixel array including a pixel that provides electrons based on photons incident on the pixel;
• and
• a sensor readout module coupled to the pixel array, said sensor readout module comprising:
• a sample module including:
• a first plurality of storage elements to store first respective reset and signal voltages as intermediate reset and signal voltages, the first reset and signal voltages corresponding to a first integration time for a pixel,
• a comparator to provide an overwrite indication signal having a first value if the difference between the first reset and signal voltages corresponds to a saturation condition of the pixel and a second value if the difference between the first reset and signal voltages does not correspond to the saturation condition,
• logic to overwrite the first reset and signal voltages with second reset and signal voltages as the intermediate reset and signal voltages if the overwrite indication signal has the first value, the second reset and signal voltages corresponding to a second integration time for the pixel that is less than the first integration time, and
• a second plurality of storage elements to store third respective reset and signal voltages corresponding to a third integration time for the pixel, wherein the third integration time is greater than the first integration time;
• and
• a pre-processing module to provide an output signal for the pixel, wherein the output signal is based on the intermediate reset and signal voltages if a difference between the third reset and signal voltages corresponds to the saturation condition, and wherein the output signal is based on the third reset and signal voltages if the difference between the third reset and signal voltages does not correspond to the saturation condition.