Abstract: Examples are disclosed that relate to determining a capacitance based on a charge accumulated on a sense capacitor electrode. One example provides a head-mounted device comprising a facial-tracking sensor, a controller, and a charge sensing circuit connected to the facial-tracking sensor. The facial-tracking sensor comprises a sense capacitor electrode configured to be positioned proximate to a surface of a face and form a capacitance based upon a distance between the sense capacitor electrode and the surface of the face, and the controller configured to apply a reference voltage to the sense capacitor electrode. The charge sensing circuit is configured to determine the capacitance of the sense capacitor electrode by determining an amount of charge accumulated on the sense capacitor electrode resulting from the reference voltage.

Abstract: A time-of-flight image sensor including a readout circuit is provided. The readout circuit may include a pixel array including multiple pixels. The pixel array may be configured to produce a pixel signal for each of one or more pixels over a series of timesteps. The pixel signal may include an illuminated value and a reset value. The readout circuit may further include a plurality of gain selection comparators configured to receive the pixel signal and select an amplifier gain value. The readout circuit may further include analog correlated double sampling circuitry. The readout circuit may further include a programmable gain amplifier configured to generate an amplified pixel signal from the pixel signal, which may be amplified at the selected amplifier gain value. The readout circuit may further include a plurality of analog-to-digital converters. Each of the analog-to-digital converters may have a common ramp generated by a global ramp generator.

Abstract: A time-of-flight image sensor including a readout circuit is provided. The readout circuit may include a pixel array including multiple pixels. The pixel array may be configured to produce a pixel signal for each of one or more pixels over a series of timesteps. The pixel signal may include an illuminated value and a reset value. The readout circuit may further include a plurality of gain selection comparators configured to receive the pixel signal and select an amplifier gain value. The readout circuit may further include analog correlated double sampling circuitry. The readout circuit may further include a programmable gain amplifier configured to generate an amplified pixel signal from the pixel signal, which may be amplified at the selected amplifier gain value. The readout circuit may further include a plurality of analog-to-digital converters. Each of the analog-to-digital converters may have a common ramp generated by a global ramp generator.