Photosite circuit using switched operational phases
AssigneeTriEye Ltd.
InventorsNadav Melamud, Avraham Bakal, Omer Kapach, Uriel Levy
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Abstract
Techniques are disclosed to accurately measure the integration or accumulation of charge measured by photosite readout circuitry due to a photodiode generated current, which is generated by a photodiode as a result of impinging light reflected onto the photodiode that forms part of an imaging sensor. The techniques described herein address shortcomings of photosite operation by using a series of sequential switching states that function to maintain the charge accumulated during idle sampling times between active detection windows.
Claims21
A photosite readout circuitry, comprising:
- an amplifier having a photodiode signal input, a reference signal input, and an amplifier output;
- a first switch configured to selectively connect or disconnect a first feedback path that couples the photodiode signal input and the amplifier output;
- and
- a second switch configured to selectively connect or disconnect a second feedback path that couples the photodiode signal input to the amplifier output via a capacitor,
- wherein the photodiode signal input is configured to receive a photodiode-generated current that results in an accumulation of a voltage across the capacitor when the photosite readout circuitry is in a first switching state,
- wherein the accumulation of the voltage across the capacitor is maintained when the photosite readout circuitry is in a second switching state,
- wherein, in the first switching state, the first switch disconnects the first feedback path and the second switch connects the second feedback path, and
- wherein, in the second switching state, the first switch connects the first feedback path and the second switch disconnects the second feedback path.
An electro-optical system, comprising:
- a plurality of photosite readout circuitries, each photosite readout circuitry from among the plurality of photosite readout circuitries comprising:
- an amplifier having a photodiode signal input, a reference signal input, and an amplifier output;
- and
- a plurality of switches configured to (i) selectively connect or disconnect a first feedback path that couples the photodiode signal input to the amplifier output, and (ii) selectively connect or disconnect a second feedback path that couples the photodiode signal input to the amplifier output via a capacitor,
- wherein the photodiode signal input is configured to receive a photodiode-generated current that results in an accumulation of a voltage across the capacitor when the photosite readout circuitry is in a first switching state, the accumulation of the voltage across the capacitor being maintained when the photosite readout circuitry is in a second switching state;
- a controller configured to, for each one of the plurality of photosites:
- control the plurality of switches to (i) operate the electro-optical system during the first switching state by disconnecting the first feedback path and connecting the second feedback path, and (ii) operate the electro-optical system during the second switching state by connecting the first feedback path and disconnecting the second feedback path;
- and
- readout circuitry configured to, for each one of the plurality of photosites, measure the accumulation of the voltage across the capacitor during one of the first switching state or the second switching state.
A method for operating a sensor that includes a photosite readout circuitry including an amplifier having a photodiode signal input, a reference signal input, and an amplifier output, the method comprising:
- controlling a plurality of switches to (i) selectively connect or disconnect a first feedback path that couples the photodiode signal input and the amplifier output, and (ii) selectively connect or disconnect a second feedback path that couples the photodiode signal input to the amplifier output via a capacitor;
- receiving, during a first phase corresponding to a first switching state, a photodiode-generated current that results in an accumulation of a voltage across the capacitor, the first switching state corresponding to the first feedback path being disconnected and the second feedback path being connected;
- measuring, during one of the first phase or a second phase corresponding to a second switching state, the accumulation of the voltage across the capacitor, the second switching state corresponding to the first feedback path being connected and the second feedback path being disconnected.
Dependencies are inferred from the claim text.