Multiband RF Front-End Circuit With Shared Output Impedance Matching
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Solution Overview
Problem
Existing multiband front end reception circuits face challenges in achieving impedance matching over a wide frequency range, particularly as the number of frequency bands increases, leading to larger impedance matching circuits and difficulty in matching output impedance across multiple bands.
Innovation Solution
A high-frequency circuit configuration with a common terminal and selection terminals, where a switch selectively connects amplifiers and impedance matching circuits to achieve impedance matching across multiple frequency bands, using parallel and serial matching circuits connected to ground, and strategically positioned inductors to improve isolation and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an impedance matching circuit is provided at the output side of the amplifier on each signal path, then impedance matching can be achieved, but the impedance matching circuit is increased in size with the increasing number of bands and it becomes difficult to achieve impedance matching over a wide band
Solution Approach 1:
A single output-side impedance matching circuit is designed to serve multiple frequency bands (first band group and second band group) through switchable configurations. The circuit can be selectively connected to match impedance for different amplifiers operating in different frequency bands, replacing the need for separate matching circuits for each band while maintaining accurate impedance matching across all bands.
Solution Approach 2:
The impedance matching circuit incorporates switching mechanisms that allow dynamic reconfiguration between different matching configurations. The circuit can be selectively connected or disconnected based on the operating frequency band, enabling the same circuit to adapt to different impedance matching requirements for different bands rather than being fixed for a single band.
2Adaptability or versatility
If multiple different frequency bands are transmitted on one signal path, then multiband operation is achieved, but it becomes difficult to achieve impedance matching at the output side of the amplifiers over a wide band
Solution Approach 1:
The frequency bands are segmented into different groups (first frequency band group and second frequency band group), each with its own dedicated amplifier and signal path. The output-side impedance matching circuit can be selectively connected to match the specific impedance requirements of each band group, allowing multiband operation while maintaining accurate impedance matching for each segment.
Solution Approach 2:
Different portions of the frequency spectrum are assigned different quality characteristics through dedicated amplifiers and selective impedance matching. Each frequency band group receives optimized impedance matching tailored to its specific requirements, rather than using a single generic matching circuit for all bands, thereby maintaining high matching accuracy across the entire wide band range.
3Manufacturing precision
If impedance matching is optimized for each frequency band separately, then matching accuracy is improved, but the overall circuit size increases
Solution Approach 1:
Multiple impedance matching circuits that would traditionally be required for different frequency bands are merged into a single shared output-side impedance matching circuit. Through selective switching, this single circuit can be configured to match the impedance requirements of different amplifiers and frequency bands, thereby achieving the same matching accuracy as separate circuits while occupying significantly less circuit area.
Data Source
AI summary
A high-frequency circuit includes a first signal path transmitting a high-frequency signal in a first frequency band group, a second signal path transmitting a high-frequency signal in a second frequency band group, a switch including a common terminal and selection terminals, a first low noise amplifier including an input terminal connected to the first signal path and an output terminal connected to a first selection terminal, a second low noise amplifier including an input terminal connected to the second signal path and an output terminal connected to a second selection terminal, and an output-side impedance matching circuit that matches impedance at the output side of the first low noise amplifier or impedance at the output side of the second low noise amplifier with a predetermined impedance with a conductive state between the a third selection terminal and the common terminal.