SPAD Quenching Circuit for Accurate Photon Detection in Bright Light
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Solution Overview
Problem
Sensing devices face challenges in accurately detecting photons in high-illuminance environments due to prolonged recharging times or inability to recharge, affecting distance measurement accuracy across a wide dynamic range.
Innovation Solution
A sensing device comprising a photodetector, transistors, and a pulse generator with a quenching section that resets internal voltages after each photon detection, allowing for quick recharging and maintaining detection accuracy regardless of illumination levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage across the SPAD terminals is lowered to the breakdown voltage to stop the avalanche phenomenon (quench), then the avalanche phenomenon is stopped, but the recharging time is prolonged or the sensing device cannot be recharged in high-illuminance environments
Solution Approach 1:
The patent applies dynamics by making the quenching voltage level adjustable rather than fixed. The voltage supply unit can dynamically change the quenching voltage level based on environmental conditions, allowing the system to adapt between different illuminance environments. This dynamic adjustment resolves the contradiction by enabling faster recharging in high-illuminance conditions while maintaining sufficient quenching effectiveness.
Solution Approach 2:
The patent changes the voltage parameter (quenching voltage level) to resolve the contradiction. By adjusting the quenching voltage level, the system can modify the recharging characteristics of the SPAD. In high-illuminance environments, a higher quenching voltage level is used to reduce recharging time, while in low-illuminance environments, a lower quenching voltage level maintains detection accuracy. This parameter change directly addresses the trade-off between detection reliability and recharging speed.
2Productivity
If the quenching voltage level is lowered to reduce recharging time, then recharging speed improves, but detection accuracy in high-illuminance environments deteriorates
Solution Approach 1:
The system dynamically adjusts the quenching voltage level based on the illuminance environment rather than using a fixed voltage level. This dynamic approach allows the system to optimize both recharging speed and detection accuracy for different operating conditions, resolving the contradiction between productivity and measurement precision.
Solution Approach 2:
The patent changes the quenching voltage parameter to resolve the contradiction. By adjusting this parameter, the system can achieve faster recharging when needed while maintaining sufficient detection accuracy. The voltage supply unit modifies the quenching voltage level according to environmental conditions, enabling the system to operate effectively across a wide dynamic range of illuminance levels.
3Adaptability or versatility
If the sensing device operates in high-illuminance environments, then the dynamic range is extended, but the ability to recharge and detect photons accurately is compromised
Solution Approach 1:
The patent applies dynamics by enabling the quenching voltage level to be adjusted according to the illuminance environment. This allows the sensing device to adapt to high-illuminance conditions while maintaining reliable photon detection. The dynamic voltage adjustment ensures the device can operate across a wide dynamic range without compromising detection reliability in any specific environment.
Solution Approach 2:
The patent changes the quenching voltage parameter to enable operation across a wide dynamic range. By adjusting this parameter based on environmental conditions, the system maintains reliable photon detection whether in high-illuminance or low-illuminance environments. This parameter adaptation resolves the contradiction between extended dynamic range and detection reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate photon detection with monotonically increasing characteristics even in high-illuminance environments, supporting a wide dynamic range and ensuring precise distance measurement.
Implementation Method 1
A single photon entering the photodiode then causes an avalanche phenomenon. The ADP that multiplies a single photon by the avalanche phenomenon is called a single-photon avalanche diode (SPAD).
Data Source
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AI summary
[Object] A sensing device is provided that is capable of detecting photons with high accuracy regardless of the environmental illuminance. [Solving Means] The sensing device of this disclosure includes: a photodetector; a load element connected interposingly between the photodetector and a first reference potential; a first transistor of the first conductivity type configured to be turned on according to a voltage of a node interposed between the photodetector and the load element; a second transistor of the first conductivity type configured to turn on a state between the first reference potential and the first transistor according to either a current of the first transistor or a voltage of a second signal line; a third transistor of the second conductivity type configured to turn on a state between the first transistor and a second reference potential according to the voltage of the second signal line; and a first inverter connected interposingly between a node interposed between the first transistor and the third transistor on one hand, and a fourth signal line on the other hand.