Self-Activating Adjustable Power Limiter Circuit
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Solution Overview
Problem
Existing limiter circuits lack fast response time, good linearity, and an adjustable threshold, and are difficult to integrate with other circuitry, especially in high-power applications.
Innovation Solution
A self-activating adjustable threshold limiter circuit using a voltage-controlled field effect transistor with capacitive coupling elements, allowing for instantaneous activation and adjustable limiting threshold, implemented using standard FET fabrication techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If prior art limiter circuits are used, then power limiting function is provided, but response time is slow
Solution Approach 1:
The patent replaces the mechanical/electronic detector-switch system with a direct voltage-controlled FET system. The FET's gate voltage directly controls the limiting action through its inherent voltage-controlled resistance characteristic, eliminating the need for separate detection and switching mechanisms. This substitution of the control mechanism achieves instantaneous response while maintaining reliable power limiting.
2Manufacturing precision
If prior art limiter circuits are used, then power limiting is achieved, but linearity is poor
Solution Approach 1:
The patent changes the operating parameter from current-controlled or power-detected switching to voltage-controlled resistance modulation. By applying a voltage proportional to the input signal amplitude to the FET gate, the FET's drain-source resistance is modulated in a linear fashion, creating a linear limiter response. This parameter change from discrete switching to continuous resistance modulation improves linearity while maintaining limiting accuracy.
3Ease of manufacture
If prior art limiter circuits are used, then limiting function is provided, but integration with other circuitry is difficult
Solution Approach 1:
The patent merges the limiting function directly into the signal path using the FET as both the control and execution element. The FET is integrated such that its gate receives the control voltage and its drain-source path directly limits the signal power to the receiver. This consolidation of control and execution functions into a single integrated component simplifies manufacturing and circuit integration while reducing overall device complexity.
4Adaptability or versatility
If adjustable threshold is added to limiter, then versatility improves, but device complexity increases
Solution Approach 1:
The patent implements threshold adjustability by changing the DC bias voltage applied to the FET gate. By varying this bias voltage, the threshold at which limiting begins can be adjusted without adding complex control circuits. This simple parameter change approach provides versatile threshold adjustment while keeping the circuit architecture simple and easy to understand.
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 provides a fast response time, improved linearity, and ease of integration with other circuitry, enabling effective power limiting in high-power applications while being easy to fabricate and tune.
Implementation Method 1
A self-activating adjustable threshold limiter circuit using a voltage-controlled field effect transistor with capacitive coupling elements
Implementation Method 2
capacitive coupling elements
Data Source
AI summary
A fast response time, self-activating, adjustable threshold limiter including a limiting element LE, a first coupling element CE.sub.1 electrically connected from a signal node of LE to a control input of LE, and a second coupling element CE.sub.2 electrically connected from the control input of LE to a nominal node of LE. An initial bias (control) voltage is also supplied to the control input of LE to dynamically control the limiting threshold for the limiter. Embodiments include usage of self-activating adjustable power limiters in combination with series switch components in a switch circuit in lieu of conventional shunt switches.