Configurable Laser Diode Driver Using Low-Voltage Resonant Pulsing
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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 GaN-based switches, which are expensive and difficult to integrate with Silicon-based architectures, limiting flexibility and efficiency.
Innovation Solution
A tunable resonant circuit with a bypass capacitor and discrete inductor is used to generate high-current pulses at low input voltages, allowing for Silicon-based switches and easy integration, enabling flexible pulse width tuning without redesigning the circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If high source voltage (40V-100V) is used to overcome parasitic inductances, then pulse width can be reduced to 5ns or less, but device complexity and cost increase due to requiring GaN FET switches
Solution Approach 1:
The patent changes the voltage parameter from high (40V-100V) to low (3.3V-5V) by using a resonant circuit topology that generates high-voltage pulses dynamically during operation. The resonant circuit uses an inductor and capacitor to create oscillating current that produces the necessary high voltage at the laser diode while the switching device only needs to handle low voltage, enabling use of standard Silicon FETs instead of expensive GaN devices
Solution Approach 2:
The resonant circuit acts as an intermediary between the low-voltage switching device and the high-voltage laser diode. The circuit includes a charging capacitor that stores energy and a resonant inductor that transforms this energy into high-voltage pulses through oscillation, mediating the voltage level mismatch and allowing standard Silicon switches to drive high-voltage laser diodes
2Duration of action of moving object
If GaN FET switches are used to withstand high voltages, then short pulse width can be achieved, but manufacturing cost and integration difficulty with Silicon-based architectures increase
Solution Approach 1:
The patent changes the operating voltage parameter of the switching device from high voltage (requiring GaN) to low voltage (compatible with Silicon). The resonant circuit topology allows the switch to operate at standard Silicon FET voltage levels (3.3V-5V) while still generating the high voltage pulses needed for short pulse width operation through resonant oscillation
Solution Approach 2:
The resonant circuit serves as a voltage transformation intermediary that decouples the voltage requirements of the switching device from those of the laser diode. This allows standard Silicon-based switching devices to be used, improving manufacturability and ease of integration with existing Silicon CMOS fabrication processes
3Ease of manufacture
If fixed circuit design is used, then manufacturing is simpler, but adaptability to different laser diode configurations (single, quad-pack, arrays) is limited
Solution Approach 1:
The patent designs a universal resonant circuit topology that can drive multiple types of laser diode configurations (single diode, quad-packs, and arrays) through configuration bits that control switching device selection. The same basic circuit architecture adapts to different applications by selectively enabling or disabling particular switching devices, providing multi-functionality without requiring multiple specialized circuits
Solution Approach 2:
The patent introduces dynamic configurability through control logic that responds to configuration bits, allowing the circuit to reconfigure itself for different laser diode arrangements. The switching devices can be selectively enabled or disabled based on the desired output configuration, making the circuit adaptable rather than fixed
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 ultra-short, high-current pulses using low input voltages, reducing costs and complexity, and allowing for integration into a single semiconductor die, while supporting a wide range of laser diode configurations.
Implementation Method 1
A first charging terminal of the charging terminals is operable to charge a first source capacitor of a first resonant circuit. The first resonant circuit includes the first source capacitor, a first inductor, and a first bypass capacitor.
Data Source
AI summary
A laser diode driver includes a clock terminal to receive a clock signal, configuration terminals to receive configuration data, drive terminals, and charging terminals. A first charging terminal is operable to charge a source capacitor of a resonant circuit that includes the source capacitor, an inductor, and a bypass capacitor. Each drive terminal is operable to be directly electrically connected to an anode or cathode of a laser diode or to ground. A mode, output selection, and grouping of drive signals that are delivered to the laser diodes are configured based on the configuration data. The laser diode driver is operable to control a current flow through the resonant circuit to produce high-current pulses through the laser diodes, the high-current pulses corresponding to a peak current of a resonant waveform developed at respective anodes of the laser diodes, a timing of the high-current pulses being synchronized using the clock signal.