Switching Circuit Isolation via LC Resonance Attenuation
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Solution Overview
Problem
In communication devices supporting multiple communication standards and frequency bands, there is a challenge in achieving sufficient isolation between different frequency signals, leading to unwanted harmonics passing through switching circuits, which affects transmission characteristics.
Innovation Solution
A switching circuit design that includes first and second switching devices connected in series and shunt configurations, respectively, with inductors forming LC series resonance circuits to attenuate unwanted signals, ensuring improved isolation characteristics by matching resonant frequencies with the signal frequencies to be attenuated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a first switching device is used to pass high frequency signals through the signal path, then signal transmission is enabled, but unwanted harmonics and leakage signals cannot be sufficiently attenuated
Solution Approach 1:
The patent introduces a second switching device as an intermediary element shunt-connected to the signal path. This second switching device acts as a mediator to divert unwanted harmonics and leakage signals to ground, thereby enhancing isolation characteristics without affecting the primary signal transmission function of the first switching device.
Solution Approach 2:
The patent extracts the harmful harmonic signals from the main signal path by using the second switching device to separate and redirect these unwanted frequencies to ground. This extraction process allows the primary switching device to focus on signal transmission while the secondary device handles the removal of harmful components.
2Reliability
If multiple switching devices are added to improve isolation characteristics, then unwanted signal attenuation improves, but device complexity increases
Solution Approach 1:
The second switching device is designed to perform multiple functions: it provides shunt connection for harmonic attenuation, enables ground routing for leakage signals, and works in coordination with the first switching device to enhance overall isolation characteristics. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The patent combines the filtering and isolation functions into a single integrated switching circuit configuration where the first and second switching devices work together. The shunt connection of the second switching device merges the harmonic attenuation and leakage signal routing functions into one cohesive structure, reducing overall circuit 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
The proposed solution effectively attenuates unnecessary signals, enhancing isolation characteristics between signal paths and improving communication device performance by directing unwanted signals to ground, thus maintaining desired transmission characteristics.
Implementation Method 1
the off capacitance of the second switching device that is in the off state and the inductor coupled in series to the off capacitance define an LC series resonance circuit. The inductance of the inductor is designed so that the resonant frequency of the LC series resonance circuit matches the frequency of a signal to be attenuated.
Data Source
AI summary
In a switching circuit, an inductance of an inductor of a shunt circuit is such that off capacitance of a second switching device that is in the off state when a first switching device is in the on state is used to define, in the shunt circuit, a series resonance circuit with a desired resonant frequency. Therefore, the frequency of an unnecessary signal to be attenuated is set to the resonant frequency of the series resonance circuit. Thus, the switching circuit achieves improved isolation characteristics with other circuits by attenuating the unnecessary signal.