Carrier Aggregation Phase Shifter With Tuned Impedance Isolation
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Solution Overview
Problem
Carrier aggregation systems face challenges in maintaining low noise figure and sufficient frequency band separation, especially when aggregating bands close in frequency, due to variations in phase shifting circuits' performance across different frequency ranges.
Innovation Solution
A carrier aggregation circuit with a mid-band path and two high-band paths, each equipped with filters and phase shifting circuits, where the mid-band filter assembly and selected high-band filters provide impedances of the same sign for imaginary parts, and a tuning circuit with an inductor couples the common node to ground to reduce the imaginary part of the mid-band filter's impedance at high-band frequencies, ensuring balanced performance across frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If phase shifting circuits are used in carrier aggregation paths, then phase adjustment capability is improved, but performance variations across different frequency ranges occur
Solution Approach 1:
The patent applies local quality by configuring different phase shifting circuits with different characteristic impedances tailored to specific frequency bands. The first phase shifting circuit is optimized for first frequency bands while the second phase shifting circuit is optimized for second frequency bands, ensuring each circuit operates at its optimal performance level for its designated frequency range.
Solution Approach 2:
The patent implements dynamics through switchable phase shifting circuits that can be selectively activated based on the operating frequency band. The switching mechanism allows the system to dynamically select the appropriate phase shifting circuit (first or second) depending on which frequency bands are being aggregated, thereby maintaining consistent performance across varying frequency conditions.
2Adaptability or versatility
If multiple frequency bands are aggregated through a common path, then carrier aggregation capability is improved, but isolation between signal paths deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the carrier aggregation system into separate first and second signal paths, each handling different frequency bands. This physical separation reduces interference between aggregated bands while maintaining the ability to aggregate multiple bands through the common output path. Each path can be independently optimized and switched.
Solution Approach 2:
The patent uses switching circuits as intermediaries to manage signal routing between the separate first and second paths and the common output path. The switches act as mediators that selectively connect appropriate paths based on the aggregation configuration, enabling flexible band combination while maintaining isolation when bands are not being aggregated together.
3Adaptability or versatility
If filters are configured for different frequency bands in carrier aggregation, then frequency band separation is improved, but impedance matching difficulties increase
Solution Approach 1:
The patent applies parameter changes by configuring filters with specific impedance characteristics matched to their designated frequency bands. The first filter is designed with impedance parameters optimized for first frequency bands, while the second filter uses impedance parameters optimized for second frequency bands. This parameter optimization simplifies impedance matching within each band while maintaining effective frequency separation.
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
This configuration achieves low loss, low noise figure, and high isolation between signal paths, improving carrier aggregation performance by balancing loading loss and maintaining ideal impedance conditions across multiple frequency bands.
Implementation Method 1
The tuning circuit can include an inductor that couples the common node to ground to provide an inductive response
Data Source
AI summary
A carrier aggregation circuit can include a mid-band path having a filter assembly and a phase shifting circuit, to support one or more frequency bands. The circuit can further include first and second high-band paths each being configured to support a frequency band and having a filter and a phase shifting circuit. Selected high-band filter and the mid-band filter assembly can be configured to provide impedances having the same sign for imaginary parts, and the phase shifting circuit of the mid-band path can be configured to provide a desired reflection coefficient phase at one of the first and second high-band frequency bands. The circuit can further include a common node coupled to outputs of the mid-band, first high-band and second high-band paths, and a tuning circuit implemented to remove the imaginary part of the impedance of the mid-band filter assembly at the frequency band of the selected high-band filter.