Magnetically Coupled Variable Inductor Circuit for 30+ GHz Tuning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional variable inductor circuits for high-frequency applications are costly due to the need for a DC voltage source and struggle to adjust inductance values effectively in high-frequency bands above 30 GHz.
Innovation Solution
A variable inductor circuit design incorporating magnetically coupled inductors, a cascode amplifier, and a control current source, where a high-frequency voltage is applied via a buffer circuit to adjust the current flowing through one inductor, thereby varying the inductance of the other inductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a gyrator-based variable inductor circuit is used to electrically adjust inductance, then inductance adjustment capability is achieved, but resonance occurs at high frequencies making adjustment difficult above 30 GHz
Solution Approach 1:
The patent replaces the traditional gyrator-based electrical adjustment mechanism with a magnetic coupling mechanism. By using magnetic coupling between inductors and controlling the current in one inductor, the effective inductance of the other inductor is adjusted without relying on high-frequency capacitive conversion that causes resonance. This substitution of the adjustment mechanism eliminates the resonance problem at high frequencies while maintaining inductance variability.
2Adaptability or versatility
If a varactor diode is used to change apparent Cgs for inductance adjustment, then inductance can be varied, but a DC voltage source around 20 V is required increasing mounting cost
Solution Approach 1:
The patent extracts and removes the expensive DC voltage source (around 20 V) and varactor diode components from the circuit. Instead, it uses a simple current source to control the current flowing through one inductor in the magnetic coupling pair. This extraction of the costly components while maintaining the core functionality of inductance adjustment directly reduces mounting cost and simplifies the circuit.
Solution Approach 2:
The patent replaces expensive varactor diodes and high-voltage DC sources with inexpensive current-source components. The current source can be implemented using simple transistor circuits that are much cheaper than varactor diodes requiring high-voltage biasing. This substitution with cheaper components achieves the same inductance adjustment function at lower cost.
3Reliability
If conventional inductors are used in matching circuits, then impedance matching is achieved, but the inductance value cannot be easily adjusted causing performance deterioration when operation frequency changes
Solution Approach 1:
The patent transforms the static inductor into a dynamic variable inductor by implementing magnetic coupling between two inductors where the current in one inductor can be dynamically controlled. This dynamic control mechanism allows the effective inductance to be adjusted in real-time, enabling the matching circuit to adapt to different operation frequencies while maintaining optimal impedance matching performance.
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
This design allows for cost-effective electrical adjustment of inductance values in high-frequency bands, suppressing mounting costs and improving the variable range of inductance while maintaining circuit performance.
Implementation Method 1
one inductor and another inductor magnetically coupled to each other
Data Source
AI summary
One inductor and another inductor are magnetically coupled to each other. A variable current source controls the current flowing in the one inductor. By controlling the current flowing in the one inductor, the inductance value of the other inductor is made variable.