HF Front-End Circuit Phase Shifting for Carrier Aggregation Isolation
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Solution Overview
Problem
Conventional RF circuits face challenges in separating different signal paths effectively, leading to interference from intermodulation products due to non-linear effects in duplexers, especially when exposed to RF signals from various frequency bands, which conventional filters cannot eliminate as these unwanted signals fall within the passband of desired signals.
Innovation Solution
An RF circuit design incorporating a diplexer for each frequency band with a phase shifter in the signal path to adapt impedance, specifically targeting harmonic frequencies, thereby reducing intermodulation products and enhancing signal separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional RF circuits are used with multiple frequency bands, then carrier aggregation capability is achieved, but intermodulation products cause interference in signal paths
Solution Approach 1:
A phase shifter is introduced as an intermediary component in the signal path between the diplexer and the second duplexer. This phase shifter specifically targets and manipulates harmonic frequencies (second and third harmonics of transmission frequencies) to prevent them from causing intermodulation products in the receive signal path, thereby resolving the interference issue while maintaining carrier aggregation capability
2Reliability
If diplexer isolation is increased to reduce intermodulation products, then signal separation improves, but circuit complexity increases
Solution Approach 1:
Instead of changing the physical structure or isolation characteristics of the diplexer, the invention changes the phase parameter of the signal path by introducing a phase shifter. This parameter change allows the system to achieve better signal separation and reduce intermodulation products without increasing the diplexer's isolation requirement, thus avoiding additional circuit complexity
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 phase shifter effectively prevents or weakens intermodulation products, improving signal isolation and quality without significant additional circuit complexity, allowing for simultaneous use of multiple frequency bands without disrupting reception.
Implementation Method 1
a phase shifter arranged in the second signal path. The phase shifter is provided to adapt the impedances of the first duplexer of the second frequency band and of the diplexer for at least one harmonic of one of the frequency bands such that at least one intermodulation product is reduced
Data Source
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AI summary
The invention relates to an HF circuit, for example for use in front-end circuits, having improved signal quality in carrier aggregation. According to the invention, a signal path between a duplexer and a diplexer comprises a phase shifter.