Event sensor pixel with sensitivity and dynamic range optimization

Abstract

A pixel circuit is provided for use in an event sensor. In one implementation, the pixel circuit includes a photosensitive element configured to generate a current signal in response to brightness of light impinging on the photosensitive element, a first N-type transistor, a second N-type transistor, a first P-type transistor including a gate connected to a first bias voltage, a second P-type transistor including a gate connected to a second bias voltage, the second bias voltage being an adjustable DC bias voltage that is adjusted according to at least one of a sensed temperature or a fabrication process variation of the pixel circuit, and a voltage output that varies in response to the brightness of light impinging on the photosensitive element. An adjustment of the second bias voltage causes a DC level of the voltage output to shift up or down without changing the overall gain of the pixel circuit. The pixel circuit may also include one or more additional N-type transistors for increasing performance by optimizing contrast sensitivity. The pixel circuit may further include a converter, a capacitor electrically coupled to the converter, and an amplifier electrically coupled to the capacitor. Further, the pixel circuit may be implemented in a stacked wafer configuration and one or more interconnects between wafers.