Series FET Constant-Current Supply for Field Emission Sources
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Solution Overview
Problem
Field emission electron sources require a power supply circuit that maintains a stable current and responds instantaneously, as existing circuits often experience performance degradation with changing currents, necessitating a solution for consistent and rapid current regulation.
Innovation Solution
A power supply circuit comprising field effect transistors coupled in series, diodes, resistors, and a voltage control module that adjusts output voltage to maintain constant current through a load, utilizing detection and control signal generation units for real-time feedback and control, allowing for instantaneous turn-on and turn-off capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional power supply circuit is used, then the circuit structure is simple, but the current stability deteriorates when the field emission electron source operates
Solution Approach 1:
The power supply circuit is divided into multiple series-connected field effect transistors (n≥2), where each transistor shares a portion of the total voltage. This segmentation allows the circuit to maintain stable current through the field emission electron source while distributing the voltage stress across multiple components, improving reliability without excessive complexity.
Solution Approach 2:
The circuit incorporates a feedback mechanism where the voltage control module continuously monitors the current through the field emission electron source and adjusts the output voltage accordingly. This feedback loop ensures constant current maintenance by dynamically compensating for any deviations, resolving the current stability issue.
2Speed
If a conventional power supply circuit is used, then the device is easy to manufacture, but the response speed is insufficient for instantaneous turn-on and turn-off
Solution Approach 1:
The field effect transistors are operated in their resistive region, allowing for dynamic and rapid adjustment of the circuit's electrical characteristics. This dynamic operation enables instantaneous turn-on and turn-off capabilities, achieving microsecond-level response speeds required for field emission electron source control.
Solution Approach 2:
The circuit utilizes changes in the electrical parameters (resistance, conductance) of the field effect transistors by adjusting their gate voltages. This parameter control allows rapid switching and response, enabling the circuit to adapt quickly to control signals while maintaining manufacturability through standard semiconductor components.
3Reliability
If high voltage is applied to achieve field emission, then the electron emission performance is improved, but the current becomes unstable and varies
Solution Approach 1:
The voltage control module employs a feedback mechanism that continuously monitors the current through the field emission electron source and adjusts the output voltage to maintain constant current. This feedback control resolves the instability caused by high voltage application while preserving the improved electron emission performance.
Solution Approach 2:
By dividing the high voltage across multiple series-connected field effect transistors, the circuit achieves both the high voltage necessary for field emission and the current stability required for consistent performance. Each transistor operates within its optimal voltage range while collectively providing the required total voltage.
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 achieves stable current operation, high voltage, and fast response times, enhancing the reliability and cost-effectiveness of field emission electron sources by sharing voltage across multiple transistors and enabling constant current control through closed-loop feedback.
Implementation Method 1
field effect transistors Si coupled in series via drains and sources in sequence... operate in a resistive region
Implementation Method 2
a source of S1 is coupled to a negative electrode of a voltage source... adjust an output voltage of the voltage source
Implementation Method 3
a first group of diodes D1i coupled in series... D11 is coupled in parallel between a gate of S2 and the negative electrode of the voltage source
Data Source
AI summary
A power supply circuit and a field emission electron source are provided. The power supply circuit includes: field effect transistors Si coupled in series via drains and sources in sequence, 1≤i≤n, i and n are natural numbers, n≥2, and a source of S1 is coupled to a negative electrode of a voltage source, and a drain of Sn is used as an output terminal of the power supply circuit to couple to a load; a first group of diodes D1i coupled in series; a first group of resistors R1j, 2≤j≤n, and i and j are natural numbers; and a voltage control module configured to adjust an output voltage of the voltage source to cause a current passing through the load to be constant; the field effect transistors Si, 1≤i≤n, operate in a resistive region.