Front-End Circuit Harmonic Filtering for Carrier Aggregation
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Solution Overview
Problem
Front-end circuits used in carrier aggregation face challenges with increased size and deteriorated reception characteristics due to harmonic components of transmission signals, especially when supporting multiple antennas or performing carrier aggregation with a single antenna.
Innovation Solution
The implementation of a front-end circuit configuration that includes a first switching circuit with common and to-be-selected terminals, connected to an antenna via a connection point, and a filter to reduce harmonic components, along with a duplexer for signal separation and impedance elements to manage signal propagation, ensuring excellent reception characteristics and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a front-end circuit is configured to support multiple antennas, then reception characteristic is improved, but the size of the front-end circuit increases
Solution Approach 1:
The patent merges multiple antenna support functions into a single antenna interface by using a switching circuit that can connect one antenna to multiple frequency bands. The first switching circuit connects the single antenna to different frequency bands (e.g., 850 MHz and 1.7 GHz) by switching between different common terminals, eliminating the need for multiple separate antenna paths while maintaining multi-band carrier aggregation capability.
Solution Approach 2:
The switching circuit and filter components are designed to serve multiple functions: the first switching circuit handles both signal routing and impedance matching across different bands, the first filter simultaneously reduces harmonic components and passes desired frequency bands, and the duplexer provides both transmission and reception paths. This multi-functionality reduces the overall component count and circuit size while supporting multiple antennas virtually.
2Volume of moving object
If a front-end circuit is configured to support one antenna, then the size of the front-end circuit is reduced, but reception characteristic deteriorates due to harmonic components
Solution Approach 1:
The patent extracts and removes the harmful harmonic components from the transmission signal using the first filter. The first filter is specifically designed to attenuate the second harmonic wave of the 850 MHz transmission signal (which falls in the 1.7 GHz reception band) while passing the desired reception signals. This extraction of harmful frequency components prevents reception characteristic deterioration.
Solution Approach 2:
The first filter acts as an intermediary component between the switching circuit and the antenna. It mediates the signal path by selectively passing desired frequency bands while blocking harmful harmonic components. The filter serves as a buffer that protects the reception path from transmission harmonics without requiring separate antenna paths.
3Volume of moving object
If carrier aggregation is performed with a single antenna, then the size of the front-end circuit is reduced, but transmission loss increases
Solution Approach 1:
The switching circuit is designed to dynamically switch between different frequency bands and signal paths. The common terminals and to-be-selected terminals are switched based on the active frequency band, optimizing the signal path for each band. This dynamic switching minimizes insertion loss by selecting the most direct path while maintaining the ability to support multiple bands through a single antenna.
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 excellent communication characteristics during carrier aggregation while minimizing the size of the front-end circuit and preventing harmonic interference, allowing for effective support of one antenna and reduced transmission loss.
Implementation Method 1
harmonic components of the transmission signals are reduced by the first filter
Implementation Method 2
a first impedance element... When the second common terminal is connected to the first impedance element, the side on which the first filter is present is opened when viewed from the connection point
Implementation Method 3
a duplexer that includes a third common terminal and first and second individual terminals... The third common terminal is connected to the antenna. The first individual terminal is connected to the connection point
Data Source
AI summary
A front-end circuit includes a switching circuit and a low-pass filter. The switching circuit includes common terminals and to-be-selected terminals. The common terminals are connected to each other, and a connection point at which the common terminals are connected to each other is connected to an antenna. The common terminal is directly connected to the connection point. The common terminal is connected to the connection point with the low-pass filter interposed there between.