RF Switch Circuit Notch Network for Isolation and Harmonic Suppression
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Solution Overview
Problem
The performance of radio frequency switch circuits in 5G mobile communication systems is compromised due to interference from radio frequency signals, leading to issues with insertion loss, isolation, and harmonic suppression, particularly as frequency bands expand and higher multi-frequency and multi-mode power amplifiers are required.
Innovation Solution
A radio frequency switch circuit incorporating a notch network connected between the negative voltage generating circuit and the logic control circuit, utilizing LC series and parallel resonant loops set to fundamental and harmonic frequencies to filter out interfering signals, thereby reducing interference and improving circuit performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a radio frequency switch circuit operates in expanded frequency bands with multi-frequency and multi-mode power amplifiers, then the communication capability is improved, but the circuit performance deteriorates due to interference from radio frequency signals
Solution Approach 1:
A notch network is introduced as an intermediary component between the negative voltage generating circuit and the logic control circuit. This notch network selectively filters out radio frequency signals at specific frequencies (including fundamental and harmonic frequencies) while allowing the negative voltage control signals to pass through, thereby protecting the logic control circuit from RF interference without affecting the expanded frequency band operation
Solution Approach 2:
The harmful radio frequency signals are extracted and removed from the control path by the notch network. The notch network is designed to specifically target and eliminate RF signals at fundamental and harmonic frequencies from the negative voltage control line, separating the useful control function from the harmful RF interference
2Productivity
If radio frequency signals are present in the negative voltage generating circuit, then the circuit can operate, but the interference degrades insertion loss, isolation and harmonic suppression performance
Solution Approach 1:
The notch network converts the harmful RF signals into a beneficial filtering action. By designing the notch network with resonant circuits tuned to specific RF frequencies, the harmful RF energy is dissipated through the resistive components of the notch network, while the desired control signals pass through unaffected, thereby improving insertion loss, isolation, and harmonic suppression 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
The notch network effectively filters out radio frequency signal interference, enhancing the radio frequency switch circuit's performance by reducing insertion loss, improving isolation, and suppressing harmonics, thus ensuring better signal transmission quality across expanded frequency bands.
Implementation Method 1
the resonant point of the first LC series resonant loop is set according to the fundamental operating frequency of the radio frequency switch circuit
Implementation Method 2
the notch network includes a first LC series resonant loop, and the resonant point of the first LC series resonant loop is set according to the fundamental operating frequency of the radio frequency switch circuit
Data Source
AI summary
A radio frequency switch circuit includes a negative voltage generating circuit, a notch network, a logic control circuit, and a radio frequency switching circuit. The logic control circuit can be configured to, upon being driven by the negative voltage signal generated by the negative voltage generating circuit, control the operating modes of the radio frequency switching circuit; and the notch network is connected between the negative voltage generating circuit and the logic control circuit. As such, the influence of radio frequency signals generated by the radio frequency switching circuit can be filtered through the notch network, and the interference of radio frequency signals to the negative voltage generating circuit can be reduced, thereby improving the performance of the radio frequency switch circuit, for example in insertion loss, isolation and harmonic suppression.