Magnetically Coupled Matching Circuit for Wideband Harmonic Suppression
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Solution Overview
Problem
Existing matching circuits in radio frequency circuits suffer from high insertion loss due to the inclusion of LC filters, which limits their ability to achieve impedance matching over a wide frequency band while also suppressing harmonic components effectively.
Innovation Solution
A matching circuit configuration that includes a first coil connected in series, a second coil connected in shunt between the ground and an input/output line, and a third coil magnetically coupled to both, with a capacitor forming a closed circuit that operates as a resonance circuit, reducing loss and maintaining impedance matching across a wide band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an LC filter circuit is used for impedance matching, then impedance matching can be achieved, but the frequency band is narrow and insertion loss increases
Solution Approach 1:
The patent combines the impedance matching function and harmonic suppression filter function into a single integrated circuit structure. The matching circuit includes series coils L1 and L2, shunt coil L3, and capacitor C, where the series coils provide impedance transformation and the shunt coil with capacitor forms a resonance circuit that suppresses harmonics. This merging eliminates the need for separate LC filter components, reducing insertion loss while maintaining wideband impedance matching capability.
Solution Approach 2:
The matching circuit is designed to perform multiple functions simultaneously: impedance matching across a wide frequency band and harmonic component suppression. The resonance circuit formed by the shunt coil L3 and capacitor C creates attenuation poles at harmonic frequencies, enabling the circuit to function as both a matching network and a filter without requiring additional components.
2Object-generated harmful factors
If a low pass filter or band pass filter is added to suppress harmonic components, then harmonic suppression is improved, but insertion loss increases due to additional inductors and capacitors
Solution Approach 1:
The patent integrates the harmonic suppression function directly into the impedance matching circuit by incorporating a resonance circuit. The shunt coil L3 and capacitor C form this resonance circuit, which creates attenuation poles at harmonic frequencies. This integration allows harmonic suppression without adding separate filter components, thereby avoiding the additional insertion loss that would result from adding independent low pass or band pass filters.
Solution Approach 2:
The matching circuit is designed to simultaneously achieve impedance matching and harmonic suppression. The resonance circuit within the matching network provides attenuation at harmonic frequencies through its attenuation poles, enabling the circuit to perform both impedance transformation and harmonic filtering in a single unified structure without requiring additional lossy filter components.
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 proposed solution achieves low insertion loss and wideband impedance matching with a predetermined attenuation pole, effectively suppressing harmonic components without increasing loss, as demonstrated by the frequency characteristic diagrams.
Implementation Method 1
the first coil and the second coil are magnetically coupled to each other
Implementation Method 2
the third coil is magnetically coupled to at least one of the first coil and the second coil
Implementation Method 3
a closed circuit including the capacitor and the third coil and being different from the input/output line is provided
Data Source
AI summary
A matching circuit includes first and second input/output ports; first, second, and third coils; and a capacitor. The first coil is connected in series between the first and second input/output ports, and the second coil is connected in shunt between a ground and an input/output line between the first and second input/output ports. The first and second coils are magnetically coupled to each other, the third coil is magnetically coupled to at least one of the first and second coils, the capacitor is directly or indirectly connected to the third coil, and a closed circuit including the capacitor and the third coil is provided.