Resonant Pulse Generator Circuit for Fast Low-Loss Laser Charging
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Solution Overview
Problem
Pulse generator circuits for laser diodes in LIDAR systems face challenges in achieving fast recharge times with minimal power dissipation, as resistive charging methods result in high energy losses and hinder miniaturization and efficiency.
Innovation Solution
A pulse generator circuit that uses a charging inductor to charge the resonant tank capacitor, allowing for non-dissipative charging by controlling the capacitor voltage to be lower or higher than the supply voltage, and incorporating a voltage regulation block for fast and efficient charging, synchronized with resonant tank activations, similar to a DC-DC converter topology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If resistive charging is used to charge the resonant tank capacitor, then the charging circuit is simple, but power dissipation is high and recharge time is long
Solution Approach 1:
The patent introduces an intermediary charging inductor between the supply voltage source and the resonant tank capacitor. This inductor enables resonant charging by forming an LC circuit with the capacitor, allowing energy transfer through oscillation rather than direct resistive connection. The inductor acts as a mediator that reduces power dissipation while enabling controlled charging, resolving the contradiction between simple circuitry and low energy loss.
Solution Approach 2:
The patent changes the charging mechanism from resistive to inductive by modifying the circuit parameters. Specifically, it introduces an inductor with specific inductance value that resonates with the capacitor at a predetermined frequency. This parameter change transforms the charging process into a resonant oscillation, dramatically reducing power dissipation while maintaining circuit controllability.
2Productivity
If resistive charging is used, then the circuit is simple, but recharge time is long
Solution Approach 1:
The charging inductor serves as an intermediary that enables faster energy transfer to the capacitor through resonant oscillation. The inductor-capacitor pair forms a tuned circuit that rapidly exchanges energy, significantly reducing recharge time compared to slow resistive charging, while adding only one primary component to the circuit.
Solution Approach 2:
The patent utilizes periodic resonant oscillation between the inductor and capacitor to achieve rapid charging. The energy is transferred through periodic exchange between magnetic field (inductor) and electric field (capacitor), completing the charging cycle in a fraction of the time required by continuous resistive charging. This periodic action enables fast recharge while maintaining circuit simplicity.
3Measurement precision
If the capacitor voltage is controlled to be lower or higher than supply voltage, then accurate charge control is achieved, but circuit complexity increases
Solution Approach 1:
The patent implements feedback control by detecting the voltage across the resonant tank capacitor and using this information to control the switching of the charging circuit. The feedback mechanism allows the circuit to automatically adjust the charging process to achieve the desired voltage level, enabling accurate charge control while using simple switching components rather than complex voltage regulation circuits.
Solution Approach 2:
The patent uses periodic switching of the charging inductor based on the resonant oscillation cycle to control the capacitor voltage. By timing the switching actions to coincide with specific phases of the resonant cycle, the circuit can achieve precise voltage control (lower or higher than supply voltage) through constructive or destructive interference of the oscillations, without requiring complex continuous regulation circuitry.
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 approach reduces power dissipation, enables accurate charge control of the resonant tank, and provides precise control of laser current, facilitating efficient and miniaturized laser diode operation in LIDAR applications.
Implementation Method 1
A pulse generator circuit uses a charging inductor to charge a resonant tank capacitor
Implementation Method 2
pulses may be generated using a resonant tank comprising a capacitor which is recharged during operation
Data Source
AI summary
An embodiment pulse generator circuit comprises a first electronic switch coupled between first and second nodes, and a second electronic switch coupled between the second node and a reference node. An LC resonant circuit comprising an inductance and a capacitance is coupled between the first and reference nodes along with charge circuitry comprises a further inductance in a current flow line between a supply node and an intermediate node in the LC resonant circuit. Drive circuitry of the electronic switches repeats, during a sequence of switching cycles, charge time intervals, wherein the capacitance in the LC resonant circuit is charged via the charge circuit, and pulse generation time intervals, wherein a pulsed current is provided to the load via the first and second nodes. The charge and pulse generation time intervals are interleaved with oscillation time intervals where the LC resonant circuit oscillates at a resonance frequency.