Frontend Filter Switching for Carrier Aggregation Leakage Suppression
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Solution Overview
Problem
Existing frontend circuits experience signal attenuation due to leakage between closely spaced receive frequency bands during carrier aggregation, leading to reduced signal quality.
Innovation Solution
Incorporation of a wide-band filter that passes multiple frequency bands, along with selective narrow-band filters, to minimize signal leakage and attenuation, reducing the need for individual narrow-band filters and minimizing size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If narrow-band filters are used for each frequency band, then signal leakage between bands is suppressed, but the number of filters increases, leading to increased device size and cost
Solution Approach 1:
The wide-band filter is designed to handle multiple frequency bands (e.g., Band 28A and Band 20) simultaneously, allowing a single filter to perform the function that previously required multiple narrow-band filters. This multi-functional approach reduces the total number of filters while maintaining effective signal separation through frequency-selective routing via switches.
Solution Approach 2:
The system employs dynamic switching between different filter configurations based on the active frequency band. Switches dynamically connect the wide-band filter or isolate it, and further dynamically route signals through appropriate narrow-band filters only when needed for specific bands, optimizing performance while minimizing component usage at any given time.
2Measurement precision
If individual narrow-band filters are used for each frequency band, then filtering precision is improved, but the device size and cost increase
Solution Approach 1:
A single wide-band filter replaces multiple narrow-band filters, reducing the physical footprint of the filter section. The wide-band filter maintains adequate filtering precision for its designated bands, and dynamic switching ensures that the same physical space can be efficiently utilized for different frequency configurations.
Solution Approach 2:
Multiple filtering functions are merged into a single wide-band filter component, consolidating what would have been separate physical filter units into one integrated element. This merging reduces overall device size while maintaining filtering effectiveness through the combination of the wide-band filter's inherent selectivity and the dynamic routing architecture.
3Device complexity
If a wide-band filter is used to pass multiple frequency bands, then the number of filters is reduced, but signal leakage between closely spaced bands may occur
Solution Approach 1:
Switches act as intermediary elements between the wide-band filter and the output stages. These switches dynamically route signals from the wide-band filter to appropriate output paths, and can also connect alternative narrow-band filters when needed. This intermediary routing mechanism prevents direct signal leakage paths while maintaining the benefits of the wide-band filter configuration.
Solution Approach 2:
The system dynamically adjusts its filtering configuration based on which frequency bands are actively being used. When closely spaced bands are simultaneously active, the system can dynamically engage additional narrow-band filtering or adjust switch positions to prevent interference, optimizing the balance between component reduction and signal isolation.
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 solution effectively suppresses signal attenuation and leakage, allowing for efficient carrier aggregation across multiple frequency bands while reducing the number of filters and components, thereby minimizing size and cost.
Implementation Method 1
a wide-band filter that passes the first communication frequency band and the second communication frequency band
Implementation Method 2
a first filter that passes the first communication frequency band selectively
Data Source
AI summary
A frontend circuit includes a wide-band filter, a transmit filter, and switches. The wide-band filter passes both the receive frequency band of a first communication frequency band and that of a second communication frequency band which is close to or overlaps that of the first communication frequency band. The transmit filter passes the transmit frequency band of the first or second communication frequency band. The switches are capable of simultaneously bringing, into conduction, at least two of multiple filters including the wide-band filter and the transmit filter. In carrier aggregation using the receive frequency bands of the first and second communication frequency bands, the switches simultaneously bring the wide-band filter and the transmit filter into conduction. Thus, in carrier aggregation using signals of multiple communication frequencies simultaneously in communication, attenuation of signals due to signal leakage in two receive frequency bands, which are close to each other, is suppressed.