Multi-Band RF Front-End Circuit With Impedance-Tuned Band Selection
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Solution Overview
Problem
Current high-frequency front-end circuits for multi-band communication systems are large and suffer from deteriorated high-frequency characteristics due to the need for multiple switches, which increase size and introduce reflection and loss.
Innovation Solution
A compact high-frequency front-end circuit design incorporating a multi-band amplifier, a communication band selection circuit, and a high-frequency processing circuit with integrated switches and passive elements, allowing for impedance frequency characteristics adjustment and extended impedance range, while reducing the number of switches and supporting multiple communication bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple switches are disposed for each communication band, then multi-band capability is achieved, but the circuit size increases and high-frequency characteristics are deteriorated
Solution Approach 1:
A single switch is designed to handle multiple communication bands by configuring different trap filters with resonant frequencies corresponding to different bands. The switch selectively connects different trap filters to the amplifier output based on the active communication band, allowing one switch to perform the function that would otherwise require multiple switches.
Solution Approach 2:
Multiple trap filters with different resonant frequencies are combined into a single filter network that can be selectively activated. The filters are connected in parallel configurations where only the appropriate filter for the current communication band is activated through the switch, merging multiple filtering functions into one integrated structure.
2Adaptability or versatility
If multiple switches are disposed for each communication band, then multi-band capability is achieved, but high-frequency characteristics are deteriorated due to reflection and loss
Solution Approach 1:
The harmful high-frequency characteristics (reflection and loss) are eliminated by removing the switch from the high-frequency signal path. Instead of placing a switch directly in the amplifier output path where it would cause reflection and loss, the invention uses the switch only to select between pre-configured trap filters, extracting the switching function from the critical high-frequency path.
Solution Approach 2:
Trap filters serve as intermediaries between the amplifier and the communication band selection switch. The filters are positioned in the signal path to perform frequency-selective attenuation, while the switch operates in a control capacity to select which filter is active, using the filter as a mediator to protect the high-frequency path from direct switch interference.
3Adaptability or versatility
If trap filters are selected by switches for different communication bands, then band selection is achieved, but the number of switches increases circuit complexity
Solution Approach 1:
A single communication band selection switch is designed to perform the function of multiple switches by connecting to multiple different trap filters. The switch configuration allows it to selectively route the amplifier output to different filter branches corresponding to different communication bands, making one switch universal for all band selection needs.
Solution Approach 2:
The filter network is segmented into multiple parallel branches, each containing a trap filter tuned to a specific communication band. The single switch segments the signal path to activate only the relevant filter branch for the current band, dividing the overall filtering function into separable segments that can be selectively engaged.
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 design achieves a smaller, more efficient high-frequency front-end circuit with improved high-frequency characteristics by eliminating switch-induced losses and extending impedance range, supporting a larger number of communication bands with enhanced signal attenuation and frequency handling.
Implementation Method 1
Bringing the first switch into or out of conduction changes the impedance frequency characteristics of the high-frequency processing circuit
Implementation Method 2
The multi-band amplifier amplifies high-frequency signals in a plurality of communication bands
Implementation Method 3
The resonant frequencies of the trap filters are set for corresponding communication bands
Data Source
AI summary
A high-frequency front-end circuit includes a communication band selection circuit, a high-frequency processing circuit, and a multi-band amplifier. The multi-band amplifier amplifies high-frequency signals in a plurality of communication bands. The communication band selection circuit is connected an output end of the multi-band amplifier. The communication band selection circuit includes a communication band selection switch. The high-frequency processing circuit is connected between a first connection line connecting the multi-band amplifier and the communication band selection circuit and a ground potential. The high-frequency processing circuit includes a passive element and an impedance selection switch. The passive element is connected between the first connection line and the ground potential. A first terminal of the impedance selection switch is connected to a second connection line connecting the passive element and the first connection line, and a second terminal of the impedance selection switch is connected to the ground potential.