Self-Matching Pulse Generator for Independent Width and Delay Control
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Solution Overview
Problem
Existing high-voltage pulse-generator circuits using transmission lines for energy storage lack independent control over pulse widths and delays, and are sensitive to varying load impedances, making them ineffective in applications where precise pulse control is required, especially in ophthalmic surgery where load impedance can be unknown or difficult to match.
Innovation Solution
The development of pulse-generator circuits that combine subcircuits with transmission-line segments and switches to allow independent control of pulse widths and delays, enabling the generation of dual-polarity pulses that can be delivered to a target without requiring impedance matching, using a power-supply subcircuit to provide DC potential and employing inverting delay-line subcircuits for flexible pulse generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a simple high-voltage pulse generator using a transmission line is used, then the circuit is simple and can generate high-voltage pulses, but the pulse width and delay cannot be independently controlled and the circuit is sensitive to load impedance variations
Solution Approach 1:
The transmission line is divided into multiple segments (first transmission line segment and second transmission line segment) that can be independently controlled. Each segment can be independently switched to ground, allowing independent control of pulse width and delay parameters without requiring a completely complex circuit redesign.
Solution Approach 2:
The circuit incorporates switches (S1, S2, S3) that dynamically connect different transmission line segments to ground at different times. This dynamic switching capability enables independent adjustment of pulse width and delay, transforming a static circuit into one with flexible, programmable control characteristics.
2Reliability
If the transmission line is used for energy storage, then high-voltage pulses can be generated, but the circuit is sensitive to varying load impedances making it ineffective when load impedance is unknown or difficult to match
Solution Approach 1:
By segmenting the transmission line into multiple independently controllable sections, the circuit can adapt to different load impedances by selectively activating appropriate segments. This segmentation allows the system to maintain reliable operation across varying load conditions without requiring precise impedance matching.
Solution Approach 2:
The circuit enables independent variation of pulse width and delay parameters through dynamic switching of transmission line segments. This parameter flexibility allows the system to adapt to unknown or varying load impedances by optimizing pulse characteristics for each specific loading condition, thereby improving both reliability and adaptability.
3Manufacturing precision
If switches are added to enable independent control of pulse widths and delays, then precise pulse control is achieved, but the device complexity increases
Solution Approach 1:
The transmission line is segmented into discrete sections (first and second segments) that can be independently controlled by individual switches. This segmentation provides precise control over pulse characteristics while keeping the number of required switches minimal, thus achieving manufacturing precision without excessive device complexity.
Solution Approach 2:
The switches in the circuit serve multiple functions: they control pulse width, adjust delay timing, and can independently manipulate different transmission line segments. This multi-functionality reduces the overall number of control elements needed, achieving precise pulse control while limiting the increase in device complexity.
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
These circuits enable precise control over pulse widths and timings, allowing for reflection-free pulse delivery to loads with varying impedances, enhancing the applicability in fields like ophthalmic surgery and other medical devices where high-voltage pulsed energy is used.
Implementation Method 1
Transmission line 100 serves as a capacitive energy-storage device
Implementation Method 2
the outer conductor of transmission line 100 is charged to voltage VSUPPLY by power supply 110, through charging resistor RC
Implementation Method 3
the value of RT is selected to match the characteristic impedance Z0 of transmission line 100. Thus, for example, a 50 ohm resistor should be used to terminate a coaxial cable segment having a nominal characteristic impedance of 50 ohms
Implementation Method 4
the closing of switch S1 simultaneously shorts both ends of the outer conductor to ground, initiating the simultaneous launch of traveling waves from both ends of the transmission line towards its center
Data Source
AI summary
Pulse-generator circuits that permit independent control of pulse widths and the delays between successive pulses. In several embodiments, a pulse-generator subcircuit includes a transmission-line segment comprising first and second conductors, configured such that the first conductor is coupled to a first DC potential. The pulse-generator subcircuit further includes a terminating resistor coupled to a first end of the second conductor of the first transmission-line segment; this terminating resistor is matched to the characteristic impedance of the transmission-line segment. The pulse-generator subcircuit further includes first and second switches, controlled by first and second timing signals, respectively, and configured to selectively and independently connect respective first and second ends of the first conductor to a second DC potential. This second potential may be ground, in some embodiments, while the DC potential supplied to the pulse-generator subcircuit by the power-supply subcircuit may range from a very small voltage to voltages exceeding a kilovolt.