Optical Load Driver Circuit Using Inductive Pulse Shaping
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Solution Overview
Problem
Time-of-flight-based measurement systems, such as LIDAR, require high power optical pulses of short duration to achieve greater distance range finding and improved resolution, but conventional driver circuits face challenges in generating narrow electrical pulses with high peak current and low ringing, especially with parasitic elements causing delays and oscillations, which are not effectively addressed by existing technologies.
Innovation Solution
A driver circuit design that includes a DC voltage source, a first circuit path for charging inductive elements, and a second circuit path with inductive, resistive, and capacitive elements in series with the optical load, where the switch transitions from closed to open states to provide high peak current electrical pulses with low ringing, utilizing parasitic inductance to generate narrow, high-repetition-rate pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional driver circuits are used to generate electrical pulses for optical loads, then the circuit structure is simple, but the pulse width is wide and peak current is limited due to parasitic elements causing delays and oscillations
Solution Approach 1:
The patent pre-charges inductive elements (parasitic or intentional) during a first time interval before the actual pulse is needed. This preliminary energy storage in the inductive elements allows for extremely fast pulse generation without requiring complex high-speed switching circuits, as the energy is already prepared and ready for immediate discharge when the switch opens.
Solution Approach 2:
The patent converts parasitic inductance, which traditionally causes harmful oscillations and delays, into a useful energy storage element. By intentionally utilizing or adding inductive elements and pre-charging them, the parasitic inductance becomes a beneficial component that enables fast pulse generation without requiring additional complex circuitry to compensate for its effects.
2Power
If conventional driver circuits generate electrical pulses, then power consumption is continuous, but peak power is limited and pulse repetition frequency is low
Solution Approach 1:
The patent employs periodic switching between two states: a first time interval where inductive elements are charged, and a second time interval where the charged inductive elements discharge to produce high peak power optical pulses. This periodic action enables high pulse repetition frequencies while maintaining low average power consumption, as the circuit alternates between energy storage and energy release phases.
Solution Approach 2:
The continuous pre-charging of inductive elements during the first time interval ensures that energy is always ready for immediate release. This preliminary energy preparation allows the system to generate high peak power pulses at high repetition rates without requiring continuous high power input, thus improving overall energy efficiency.
3Shape
If conventional driver circuits are used, then the circuit is easy to operate, but pulse rectangularity is poor and ringing occurs
Solution Approach 1:
The patent converts the harmful effect of parasitic inductance into a beneficial mechanism for generating clean, rectangular pulses. By pre-charging the inductive elements and then abruptly opening the switch, the stored magnetic energy discharges through a controlled path, producing a sharp rectangular pulse without the oscillations and ringing that typically plague conventional circuits. The parasitic inductance becomes part of the pulse-forming network rather than a source of distortion.
4Duration of action of moving object
If narrow pulses with high peak current are generated, then optical pulse width is reduced, but circuit complexity increases to manage parasitic elements
Solution Approach 1:
The patent extracts and isolates the inductive energy storage function into a dedicated first circuit path with a switch, separating it from the optical load drive path. This extraction allows the inductive elements to be pre-charged independently without affecting the optical load, and then discharged cleanly to produce narrow pulses. The separation simplifies the overall circuit design by clearly defining the energy storage and energy delivery functions.
Solution Approach 2:
The patent prepares the inductive elements in advance during a first time interval, storing energy without requiring the optical load to be connected or the pulse to be immediately generated. This preliminary energy preparation enables the subsequent optical pulse to be extremely narrow and high-peaked, as all the energy is ready for instantaneous release without requiring complex high-speed switching or energy transfer mechanisms.
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 driver circuit achieves optical pulses with widths ranging from 30 picoseconds to 1,000 picoseconds, enabling higher peak power, improved rectangularity, and increased pulse repetition frequency, simplifying distance measurements and enhancing the performance of time-of-flight-based measurement systems while reducing total power consumption.
Implementation Method 1
one or more inductive elements, wherein the switch being in the closed state is to cause current to charge the one or more inductive elements through the first circuit path; and a second circuit path to connect to the optical load, wherein the second circuit path includes: the one or more inductive elements... the switch being in the open state is to cause the one or more inductive elements to discharge current through the second circuit path
Data Source
AI summary
A driver circuit, for generating narrow electrical pulses of high repetition rate with high peak current and low after pulse ringing to drive an optical load, may include a source, a first circuit path, and a second circuit path. The first circuit path may be connected to the source and may include inductive elements and a switch. The switch being in a closed state may charge current in the inductive elements through the first circuit path. The second circuit path may connect to the optical load and may be connected to the source. The second circuit path may include the inductive elements and a capacitive element in series with the optical load. The switch transitioning from the closed state to an open state may discharge current from the inductive elements through the second circuit path to provide an electrical pulse to the optical load.