LiDAR APD Bias Compensation for Temperature-Stable Signal Gain
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Solution Overview
Problem
Conventional LiDAR systems using avalanche photo diodes face challenges in maintaining optimal operating conditions due to temperature fluctuations and the need to avoid excessive noise and signal saturation, which affect data accuracy and reliability.
Innovation Solution
A LiDAR system with a scanning system that includes an avalanche photo diode (APD) and a variable voltage source, controlled by a controller to adjust the bias voltage based on temperature readings, ensuring the bias voltage does not exceed the avalanche voltage threshold, and employing bias voltage calibration to determine optimal operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the bias voltage is increased to improve signal gain, then the signal detection capability is improved, but the noise increases and signal saturation occurs
Solution Approach 1:
The patent implements dynamic bias voltage adjustment by continuously monitoring the APD temperature and calculating the optimal bias voltage in real-time based on the temperature-dependent avalanche threshold, rather than using a fixed bias voltage. This dynamic adaptation allows the system to maintain optimal signal gain while avoiding noise and saturation conditions that occur with static high bias voltage settings.
Solution Approach 2:
The system employs a feedback mechanism where the temperature sensor continuously monitors APD temperature, the controller calculates the current avalanche threshold based on this temperature, and adjusts the bias voltage accordingly. This closed-loop feedback ensures the bias voltage remains optimized for signal gain while staying below the temperature-varying avalanche threshold to prevent noise and saturation.
2Reliability
If the bias voltage is adjusted to avoid signal saturation, then the reliability is improved, but the signal gain may be reduced
Solution Approach 1:
The patent changes the bias voltage parameter dynamically based on temperature conditions. By calculating the avalanche threshold as a function of temperature and setting the bias voltage to a predetermined percentage below this threshold, the system adapts the operating parameters to maintain both reliability and optimal signal gain across varying environmental conditions.
3Measurement precision
If the avalanche voltage threshold is used as the bias voltage, then the signal gain is maximized, but the APD operates at breakdown point causing excessive noise
Solution Approach 1:
The system takes preliminary anti-action by deliberately setting the bias voltage below the avalanche threshold (at a predetermined percentage distance) rather than at the threshold itself. This preventive approach anticipates the noise generation that would occur at breakdown and avoids it proactively, while still maintaining sufficiently high signal gain for effective operation.
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 system maintains accurate signal gain and reduces noise by dynamically adjusting the bias voltage, enhancing data processing and object detection capabilities under varying environmental conditions.
Implementation Method 1
avalanche photo diodes for detecting returns of laser pulses
Implementation Method 2
avalanche photo diode (APD) having first and second terminals, the APD having an avalanche voltage threshold
Data Source
AI summary
Embodiments discussed herein refer to LiDAR systems that use avalanche photo diodes for detecting returns of laser pulses. The bias voltage applied to the avalanche photo diode is adjusted to ensure that it operates at desired operating capacity.