APD Bias Switching Circuit for Heat and Voltage Spike Control
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Solution Overview
Problem
Avalanche photodetection devices generate excessive heat when biased, leading to potential damage and reduced detection accuracy, and the reading circuit can be damaged by voltage fluctuations due to switching states in existing photodetection systems.
Innovation Solution
The photodetection device incorporates a configuration with multiple terminals and circuit units, including switches, resistors, capacitors, and transimpedance amplifiers, allowing for controlled bias voltage application to avalanche photodiodes, reducing heat generation and voltage fluctuations by switching between different potential differences, and utilizing a switch control unit to manage these states based on detection timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bias voltage is applied to avalanche photodiode to enable light detection, then detection capability is improved, but heat generation increases causing potential damage and reduced accuracy
Solution Approach 1:
The patent applies periodic action by switching the bias voltage to the avalanche photodiode in alternating intervals. During detection periods, high bias voltage is applied to enable avalanche multiplication and improve detection accuracy. During non-detection periods, the bias voltage is reduced or removed to minimize heat generation. This periodic switching between high and low voltage states resolves the contradiction between detection capability and heat generation.
Solution Approach 2:
The patent implements dynamics by making the bias voltage adjustable and switchable rather than fixed. The system dynamically changes the voltage state based on detection requirements, transitioning between conductive and cutoff states. This dynamic control allows the system to optimize detection performance when needed while minimizing thermal effects during idle periods.
2Temperature
If switch is used to stop bias voltage application to suppress heat generation, then heat generation is reduced, but voltage fluctuation damages reading circuit
Solution Approach 1:
The patent introduces an intermediary voltage buffer between the switch and the reading circuit. When the switch transitions between conductive and cutoff states, the buffer circuit absorbs and smooths the resulting voltage fluctuations, preventing direct transmission of shock voltages to the reading circuit. This intermediary element resolves the contradiction by allowing switch-based heat suppression while protecting the reading circuit from voltage damage.
3Adaptability or versatility
If multiple avalanche photodiodes are used to increase detection coverage, then detection capability is improved, but total heat generation increases
Solution Approach 1:
The patent extends periodic action to multiple avalanche photodiodes by controlling them in time-division multiplexed manner. Different photodiodes are activated in alternating time slots rather than simultaneously. This allows the system to maintain broad detection coverage across multiple sensors while ensuring that at any given moment, fewer diodes are active, thereby reducing the total heat generation from all diodes combined.
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
This configuration effectively suppresses heat generation in avalanche photodiodes and minimizes damage to the reading circuit from voltage fluctuations, enhancing the accuracy and reliability of the photodetection device.
Implementation Method 1
When light enters the avalanche photodiode while the bias voltage is being applied, the avalanche photodiode multiplies and outputs electrons generated in response to the incident light
Implementation Method 2
The reading circuit includes a transimpedance amplifier
Implementation Method 3
The second circuit unit includes a second switch, a capacitor, and a reading circuit
Implementation Method 4
The first circuit unit includes a first switch and a resistor
Data Source
AI summary
A first terminal is connected to a first electrode of an APD. First and second circuit units and are connected in parallel with each other to a second electrode of the APD. A second terminal is connected to the second electrode via the first circuit unit. A third terminal is connected to the second electrode via the second circuit unit. A first switch, a resistor, the second electrode, and the second terminal are connected in series with each other. A second switch and a capacitor are connected in parallel with each other to the second electrode. The second switch, the second electrode, and a third terminal are connected in series with each other. A TIA is connected in series with the capacitor and is connected to the second electrode via the capacitor.