Carrier Aggregation Phase Shifter Tuning for Impedance Control
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Solution Overview
Problem
Carrier aggregation systems face challenges in maintaining low noise figure and sufficient frequency separation between aggregated bands, especially when bands are close in frequency, requiring efficient impedance management and phase shifting to achieve optimal performance.
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 with the same sign for imaginary parts, and a tuning circuit with an inductor couples the common node to ground to remove or reduce the imaginary part of the mid-band filter impedance at high-band frequencies, allowing for desired reflection coefficient phases across multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is implemented with multiple frequency bands, then data rate capability is improved, but impedance management complexity increases
Solution Approach 1:
A tuning circuit is introduced as an intermediary component between the mid-band filter assembly and the common node. This tuning circuit actively manages impedance by providing a compensating imaginary component that cancels out the mid-band filter's imaginary impedance at high-band frequencies, thereby simplifying overall impedance management while enabling multi-band carrier aggregation
Solution Approach 2:
The patent adjusts impedance parameters dynamically by changing the tuning circuit's electrical characteristics. The tuning circuit is designed to provide specific impedance values (with opposite sign imaginary parts) that compensate for frequency-dependent impedance variations, allowing the system to maintain optimal performance across multiple frequency bands
2Productivity
If frequency bands are aggregated that are close in frequency, then spectral efficiency is improved, but frequency separation is reduced
Solution Approach 1:
The patent applies different impedance management strategies to different frequency bands. The tuning circuit is specifically designed to provide compensation at high-band frequencies while allowing mid-band frequencies to operate with their native filter characteristics, creating localized optimization for each band's specific requirements
3Device complexity
If a common path is used for multiple frequency bands, then device complexity is reduced, but noise figure increases
Solution Approach 1:
The common path is segmented into frequency-specific sections using bandpass filters for mid-bands and high-bands. This segmentation allows each frequency band to be processed through optimized filter sections before combining at the common node, maintaining low noise figure while using a shared overall architecture
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 enhances carrier aggregation performance by maintaining low noise figure, reducing impedance variations, and achieving balanced trade-offs between frequency bands, improving data rate capabilities and signal processing efficiency.
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.