PA Matching Circuit With Resonant Feedback for Low-Frequency Clutter
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Solution Overview
Problem
The increase in gain of radio frequency power amplifiers in mobile phones leads to excessive amplification of low-frequency clutter signals, affecting communication quality by causing PA spurs.
Innovation Solution
A matching circuit structure with a frequency selective input matching network, comprising a resonant capacitor and inductor in parallel, connected in series with a matching inductor and ground, and a negative feedback network, which reduces low-frequency signal amplification capability by increasing negative feedback impedance at low frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the gain of the power amplifier is increased to ensure high transmission power, then the transmission power is improved, but the amplification of low-frequency clutter signals increases, leading to excessive PA spurs and degraded communication quality
Solution Approach 1:
The patent applies local quality by designing a frequency-selective input matching network that provides different impedance characteristics at different frequency bands. The matching network is optimized to present high impedance at low frequencies (to suppress clutter) while maintaining good matching at the operating frequency band, thereby locally tailoring the impedance properties to different frequency regions rather than using a uniform matching approach
Solution Approach 2:
The patent utilizes parameter changes by varying the impedance parameters of the input matching network across different frequency ranges. Through careful selection of matching elements (inductors and capacitors), the network transforms the input impedance to achieve high impedance at low frequencies for clutter suppression while maintaining appropriate impedance at the operating band for power amplification
2Power
If the gain of the power amplifier is increased to meet high power transmission requirements, then the transmission power is improved, but the low-frequency signal amplification capability increases, causing excessive clutter amplification
Solution Approach 1:
The frequency-selective input matching network provides localized impedance transformation that creates high impedance specifically at low frequencies while maintaining good matching at the operating frequency band. This allows the amplifier to have high gain at the desired band without proportionally amplifying low-frequency clutter signals
Solution Approach 2:
The input matching network performs preliminary frequency-selective impedance transformation before the signal enters the power amplifier stages. By establishing the frequency-dependent impedance characteristics at the input stage, the network pre-conditioned the signal path to suppress low-frequency components before they can be amplified by subsequent stages
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
Effectively suppresses low-frequency clutter signals, reducing transmission gain and improving communication quality by preventing amplification of low-frequency signals in the power amplifier.
Implementation Method 1
the resonant capacitor C1 and resonant inductor L connected in parallel to transmission end of the PA resonate at low frequencies, thereby increasing the negative feedback impedance of a first-stage low-frequency part
Data Source
AI summary
A matching circuit structure for effectively suppressing the low-frequency clutter of a power amplifier of a mobile phone, falling within the technical field of radio frequency Pas is provided. The circuit structure includes an input end, a blocking capacitor, a power amplifier (PA), an output matching network and an output end connected in series; and the matching circuit structure further includes a negative feedback network connected in parallel to a transmission end of the PA; the negative feedback network includes a resonant capacitor, a resonant inductor and a matching inductor; the resonant capacitor and the resonant inductor are connected in parallel to form a frequency selecting network, and the frequency selecting network is connected in series with the matching inductor and to the ground. The matching circuit structure above can be used to effectively suppress the low-frequency clutter of a power amplifier.