Pixel circuit including an open-loop amplifier with well controlled gain for event-based vision sensor and method of controlling thereof

A pixel circuit for use with an event-based vision sensor, the pixel circuit comprising:

• a photosensitive element configured to generate a current signal in response to brightness of light impinging on the photosensitive element;
• a converter configured to receive the current signal from the photosensitive element and generate a voltage signal based on the received current signal;
• a capacitor electrically coupled to the converter in series and configured to receive the voltage signal from the converter;
• an open-loop amplifier electrically coupled, at an input, to the capacitor in series and configured to generate, at an output, an amplified signal based on an output signal from the capacitor, wherein there is no feedback between the output and the input of the open-loop amplifier, and further wherein the open-loop amplifier comprises a plurality of stacked transistors providing a well-controlled and high-accuracy open-loop gain of the open-loop amplifier, wherein a gate of at least one of the plurality of stacked transistors is configured to receive a bias voltage that sets an operation point of the open-loop amplifier;
• and
• a reset device electrically coupled between the input and the output of the open-loop amplifier and configured to reset the open-loop amplifier when a trigger signal is generated.

A method for controlling an event-based vision sensor including a plurality of pixels, comprising:

• receiving a current signal in response to light impinging on a photosensitive element;
• converting the current signal to a voltage signal;
• generating a decoupled voltage signal by a capacitor based on the voltage signal, wherein the decoupled voltage signal is decoupled from the current signal;
• generating an amplified signal by an open-loop amplifier based on the decoupled voltage signal, wherein there is no capacitive feedback between the amplified signal and the decoupled voltage signal, and further wherein the open-loop amplifier comprises a plurality of stacked transistors providing a well-controlled and high-accuracy open-loop gain of the open-loop amplifier, wherein a gate of at least one of the plurality of stacked transistors is configured to receive a bias voltage that sets an operation point of the open-loop amplifier;
• generating a trigger signal when the amplified signal matches a condition;
• and
• resetting the open-loop amplifier when the trigger signal is generated.