Configurable Laser Diode Driver With Tunable Resonant Pulse Circuit
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Solution Overview
Problem
Conventional pulsed laser diode driver circuits face challenges in generating short, high-current pulses due to parasitic inductances, requiring high voltages and relying on fixed parasitic capacitances and inductances, which limits pulse width and repetition frequency, and often necessitate complex bootstrap circuitry for multi-channel laser diodes.
Innovation Solution
A configurable high-frequency pulsed laser diode driver with a tunable resonant circuit and refresh circuit that uses a discrete inductor and bypass capacitor to generate ultra-short pulses, allowing for adjustable pulse width and peak current, and eliminates the need for bootstrap circuitry by using N-type switches, enabling operation at lower input voltages and higher repetition frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If high source voltage (greater than 40V-100V) is used to overcome parasitic inductances, then the desired short pulse width (5 ns or less) is achieved, but the device complexity and power dissipation increase
Solution Approach 1:
The patent changes the voltage parameter from high (40V-100V) to low (5V-15V) by modifying the circuit topology to include a series resonant circuit with capacitor and inductor. This parameter change enables the generation of high-current pulses without requiring high source voltage, thereby reducing device complexity and power dissipation while maintaining short pulse width performance
Solution Approach 2:
The patent replaces the conventional voltage-based pulse generation mechanism with a current-based resonant oscillation mechanism. By using a series resonant circuit composed of capacitor, inductor, and laser diode, the system generates high-current pulses through resonant oscillation rather than relying on high voltage, thus simplifying the overall device structure
2Duration of action of moving object
If high source voltage is used to achieve short pulse width, then the pulse width requirement is met, but power dissipation increases
Solution Approach 1:
The patent changes the operating voltage parameter from high (40V-100V) to low (5V-15V) by implementing a series resonant circuit topology. This parameter change significantly reduces power dissipation (P=V²/R) while maintaining the ability to generate short pulses through resonant current oscillation in the LC circuit
Solution Approach 2:
The patent converts the typically harmful parasitic inductances into useful resonant inductances by intentionally including them in the series resonant circuit. The bond wire inductances and parasitic inductances become part of the resonant circuit's total inductance, enabling the circuit to generate high-current pulses through resonance rather than requiring high voltage to overcome them
3Device complexity
If conventional pulsed laser diode driver circuits are used, then the circuit structure is simple, but the pulse repetition frequency is limited
Solution Approach 1:
The patent implements periodic action through the series resonant circuit that naturally oscillates at its resonant frequency. The capacitor charges and discharges periodically through the laser diode and inductor, generating repetitive high-current pulses without requiring complex refresh circuitry, thereby enabling high pulse repetition frequencies with simple circuit structure
Solution Approach 2:
The patent uses the capacitor to pre-store energy before each pulse generation. The capacitor is charged during the off-period and then rapidly discharged through the laser diode during the on-period, enabling quick pulse repetition. This preliminary energy storage action allows high repetition frequencies without requiring complex refresh mechanisms
4Device complexity
If fixed parasitic capacitances and inductances are used, then the circuit design is simplified, but the pulse width and peak current are limited
Solution Approach 1:
The patent transforms the fixed parasitic elements into dynamic resonant elements. By configuring the circuit as a series resonant system, the capacitor and inductor values can be selected to achieve desired resonant frequency, pulse width, and peak current. The resonant oscillation dynamically adjusts the current waveform characteristics, enabling tunable pulse parameters while maintaining simple circuit design
Solution Approach 2:
The patent converts the harmful fixed parasitic inductances and capacitances into beneficial resonant elements. The bond wire inductances and package capacitances become integral parts of the resonant circuit, determining the oscillation frequency and pulse characteristics. This approach enables high peak current generation without requiring additional complex components
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 solution enables the generation of high-current, ultra-short pulses with adjustable parameters, improving the efficiency and flexibility of pulsed laser diode drivers, reducing power dissipation, and simplifying the design by eliminating the need for high voltages and complex circuitry.
Implementation Method 1
A first inductor of the pulsed laser diode driver has a first terminal that is directly electrically connected to the first terminal of the first source capacitor
Implementation Method 2
A first source capacitor of the pulsed laser diode driver has i) a first terminal directly electrically connected to the refresh circuit to receive the refresh current and to develop the source voltage therefrom
Implementation Method 3
produce a high-current pulse through a first laser diode, the high-current pulse corresponding to a peak current of a resonant waveform developed at an anode of the first laser diode
Data Source
AI summary
A pulsed laser diode driver includes a refresh circuit configured to generate a refresh current using a received input voltage. A current amplitude of the refresh current is controlled by the refresh circuit based on a voltage level of a source voltage received by the refresh circuit. A source capacitor of the pulsed laser diode driver is configured to receive the refresh current and to develop the source voltage therefrom. An inductor of the pulsed laser diode driver has a first terminal that is directly electrically connected to the source capacitor. One or more switches of the pulsed laser diode driver are configured to control a current flow through the inductor to produce a high-current pulse through a laser diode that corresponds to a peak current of a resonant waveform developed at an anode of the laser diode.