SPAD Light Receiver Clamping Circuit for Readout Overvoltage Protection
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Solution Overview
Problem
Light receiving devices, particularly those using SPAD elements, are vulnerable to overvoltage when irradiated with excessive laser light, which can lead to circuit element breakdown in the readout circuit.
Innovation Solution
Incorporating a protection circuit between the light receiving element and the readout circuit, which includes a clamping circuit to limit overvoltage. The clamping circuit consists of a resistance element, a first clamping element (such as a clamping diode), and an optional second clamping element (such as a MOS transistor).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light receiving element (such as SPAD) is used to detect photons, then high sensitivity and single-photon detection capability are achieved, but the circuit becomes vulnerable to overvoltage damage when exposed to excessive light
Solution Approach 1:
A protection circuit is introduced as an intermediary component between the light receiving element and the readout circuit. This protection circuit includes a clamping circuit with a resistance element and clamping elements (such as diodes or transistors) that act as mediators to limit voltage spikes and protect downstream circuit elements from overvoltage damage while allowing normal signal transmission
Solution Approach 2:
The protection circuit is designed to preemptively counteract potential overvoltage damage before it can reach the readout circuit. The clamping elements are configured to activate when voltage exceeds a safe threshold, creating a preliminary protective barrier that prevents harmful voltage levels from propagating through the circuit
2Device complexity
If the light receiving element is directly connected to the readout circuit, then signal transmission is simple and direct, but excessive light causes overvoltage that can break circuit elements
Solution Approach 1:
A protection circuit is introduced as an intermediary component between the light receiving element and the readout circuit. This protection circuit includes a clamping circuit with a resistance element and clamping elements (such as diodes or transistors) that act as mediators to limit voltage spikes and protect downstream circuit elements from overvoltage damage while allowing normal signal transmission
Solution Approach 2:
The protection circuit uses relatively simple and cost-effective components (resistance elements, diodes, or transistors) that can be easily integrated into the circuit. These components serve as sacrificial protective elements that can be designed to fail safely or be replaced if needed, providing an economical solution to the overvoltage problem
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
The protection circuit effectively clamps overvoltage to a safe level, preventing damage to circuit elements in the readout circuit even when the light receiving element is exposed to excessive light.
Implementation Method 1
a light receiving element that generates a signal in response to reception of a photon
Data Source
AI summary
A light receiving device according to the present disclosure includes: a light receiving element that generates a signal in response to reception of a photon; a readout circuit that reads out a signal generated by the light receiving element; and a protection circuit that is provided between the light receiving element and the readout circuit and protects a circuit element of the readout circuit from overvoltage. Further, a distance measuring device according to the present disclosure includes a light receiving device of the above configuration.