TECHNICAL FIELD

The present disclosure is generally related to time-of-flight (TOF) systems, and more particularly to achieving high dynamic range in a receiver associated with a TOF system.

BACKGROUND

An emerging category of electronic devices is time-of-flight (TOF) systems. The TOF systems find applications in accelerometers, monolithic gyroscopes, light sensors, conveyor belts, depth sensing, proximity sensing, gesture recognition and imagers. A TOF system includes a light source that emits light pulses. The light pulses are emitted towards a target, which reflects the light pulses. The target is any object of interest which may include, but not limited to, a human, an automated component, an animal, an electronic device etc. A TOF sensor in the TOF system receives the reflected light pulses. The TOF sensor receives the reflected light pulses after a time of flight, which is proportional to a distance of the target from the TOF system.

The TOF sensor includes one or more TOF sensor pixels. Each TOF sensor pixel includes a receiver. The receiver processes the reflected light pulses to estimate the distance of the target from the TOF system. In addition to the reflected light pulses, the receiver also receives other signals such as, but not limited to, electrical interferences, crosstalk signals and ambient light. The ambient light is due to one or more of the following, but not limited to, florescent lamps, sunlight, bulbs etc.

The ambient light causes a direct current (DC) signal being generated in the receiver. A high DC signal saturates the receiver. This causes an error in estimating the distance of the target from the TOF system. In one example, a signal strength of the reflected light pulse is 30 dB whereas an interference generated is of the order of 100 dB. Thus, a receiver with high dynamic range is required.

SUMMARY

According to an aspect of the disclosure, a receiver is disclosed. The receiver includes a photodiode that generates a current signal. A coupling capacitor is coupled to the photodiode, and generates a modulation signal in response to the current signal received from the photodiode. A sigma delta analog to digital converter (ADC) is coupled to the coupling capacitor, and generates a digital data in response to the modulation signal. A digital mixer is coupled to the sigma delta ADC, and generates an in-phase component and a quadrature component corresponding to the digital data. A processor is coupled to the digital mixer, and processes the in-phase component and the quadrature component corresponding to the digital data.

