Multi-Mode RF Circuit With Switchable Impedance for Carrier Aggregation
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Solution Overview
Problem
Conventional RF front-end circuits in mobile communication devices face challenges in presenting optimal out-of-band impedance during carrier aggregation, particularly when frequency bands are close, leading to ineffective interference mitigation.
Innovation Solution
A multi-mode RF circuit with a switchable filter circuit and a switching circuit coupled to an RF front-end circuit, which can selectively provide different inherent impedances to mitigate interference by configuring the circuit to support various frequency bands through a control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an adjustable capacitor is used to influence out-of-band impedance, then the impedance can be tuned, but the impedance level is insufficient to mitigate interference during carrier aggregation
Solution Approach 1:
The patent changes the impedance parameter by introducing a switchable impedance circuit that can present different impedance values (first impedance and second impedance) to different frequency bands. This allows the filter circuit to present higher out-of-band impedance levels that effectively mitigate interference during carrier aggregation, resolving the limitation of conventional adjustable capacitors.
Solution Approach 2:
The switchable impedance circuit acts as an intermediary between the filter circuit and the output node. It selectively couples different impedance elements based on the operating frequency band, providing the necessary impedance transformation to achieve effective interference mitigation while maintaining adaptability across different carrier aggregation configurations.
2Productivity
If a filter circuit is designed for a selected frequency band, then it can communicate RF signals in that band, but it presents insufficient out-of-band impedance to mitigate interference from other bands
Solution Approach 1:
The patent makes the impedance characteristics dynamic by introducing a switchable impedance circuit that can change its impedance presentation based on the operating mode. The circuit dynamically switches between different impedance configurations to provide appropriate out-of-band rejection for different frequency band combinations during carrier aggregation, while maintaining full communication capability in the selected band.
3Device complexity
If conventional RF front-end circuits are used, then the device structure is simple, but interference mitigation during carrier aggregation is ineffective
Solution Approach 1:
The patent merges the filter circuit and the impedance control function into a single integrated switchable impedance circuit. This combination achieves effective interference mitigation during carrier aggregation without requiring separate complex impedance matching networks, thus improving performance while maintaining relatively simple device structure.
Data Source
AI summary
A multi-mode radio frequency (RF) circuit is provided. The multi-mode RF circuit is configured to support simultaneous communication in a pair of different frequency bands via an output node(s) coupled to an RF front-end circuit. A switchable filter circuit is configured to communicate one RF signal in a selected frequency band, while a multi-band filter circuit(s) is configured to communicate second RF signal in other frequency bands outside the selected frequency band. The switchable filter circuit is preconfigured to present various inherent impedances against each of the other frequency bands. A switching circuit is provided between the switchable filter circuit and the output node(s). In various operation modes, the switching circuit is configured to selectively provide one of the various inherent impedances to the output node(s), thus helping to mitigate interference caused by any of the other frequency bands used to support simultaneous communication with the selected frequency band.