Split LNA Topology for Carrier Aggregation Band Isolation
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Solution Overview
Problem
Current receiver front end circuits face challenges in achieving high output-to-output isolation, maintaining linearity, and minimizing noise figure when operating in Split mode, especially when handling carrier aggregation signals across broad frequency ranges.
Innovation Solution
The proposed receiver front end circuit employs a flexible and efficient design with multiple low noise amplifiers (LNAs) and a split LNA configuration, allowing for independent control of each LNA to optimize signal amplification and processing for single-band and multi-band RF signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single LNA is used to amplify both intraband CA signals and interband CA signals across broad frequency ranges, then the device complexity is reduced, but the isolation between different frequency bands deteriorates
Solution Approach 1:
The LNA is divided into multiple independent amplifiers (first LNA for lower frequency band, second LNA for upper frequency band) instead of using a single broadband amplifier. Each LNA is optimized for specific frequency ranges, achieving better isolation between bands while maintaining manageable device complexity through modular architecture.
Solution Approach 2:
The system dynamically selects which LNA to activate based on the frequency band of the received signal. A frequency detection mechanism determines whether to enable the first LNA (for intraband CA) or the second LNA (for interband CA), optimizing performance for each operating condition rather than relying on a fixed single-LNA configuration.
2Object-generated harmful factors
If multiple LNAs are used to handle different frequency bands, then the isolation between bands is improved, but the device complexity increases
Solution Approach 1:
Each LNA is designed with multi-functionality to handle multiple signal types within its optimized frequency band. The first LNA can process both intraband CA signals and non-CA signals in the lower band, while the second LNA handles interband CA signals in the upper band. This universal design reduces the need for even more specialized amplifiers, balancing isolation improvement with controlled complexity.
Solution Approach 2:
A frequency detection circuit acts as an intermediary between the antenna and the multiple LNAs, automatically determining which LNA should be activated based on the received signal's frequency characteristics. This intermediary component simplifies the control logic and reduces the complexity of managing multiple LNAs by providing automated frequency-based routing.
3Adaptability or versatility
If the LNA operates over a broad frequency band to handle both intraband and interband carrier aggregation, then the adaptability is improved, but the noise figure and linearity deteriorate
Solution Approach 1:
The broad frequency band coverage is achieved through segmentation into two separate LNA modules, each optimized for a specific frequency range. The first LNA covers the lower frequency band with optimized noise figure and linearity for intraband CA, while the second LNA covers the upper frequency band with optimized parameters for interband CA. This segmentation allows each LNA to maintain high reliability within its designated band rather than compromising performance across the entire broad spectrum.
Solution Approach 2:
The system dynamically adapts to different frequency bands by selectively activating the appropriate LNA based on signal detection. When intraband CA signals are detected in the lower band, the first LNA is activated; when interband CA signals are detected in the upper band, the second LNA is activated. This dynamic adaptation maintains optimal noise figure and linearity for each operating condition while preserving overall system versatility.
4Device complexity
If a passive splitter is used to divide the amplified signal for intraband CA, then the device complexity is reduced, but the isolation between output signals deteriorates
Solution Approach 1:
The harmful function of the passive splitter (poor isolation) is extracted and replaced by taking out the signal splitting function entirely. Instead of using a passive splitter that divides the amplified signal, the invention uses two separate LNAs that independently amplify different frequency bands. This extraction of the splitting function eliminates the isolation problem while maintaining the ability to handle intraband CA signals through frequency-based separation.
Data Source
AI summary
A receiver topology for supporting various combinations of interband carrier aggregation (CA) signals, intraband non-contiguous CA and non-CA signals having different combinations of signals aggregated therein.