Dual-LNA Switching Circuit for Internal-External RF Gain Paths
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Solution Overview
Problem
Existing wireless communication devices face challenges in efficiently switching between internal and external low noise amplifier configurations, leading to performance degradation and increased costs due to the use of external antenna multiplexer switches.
Innovation Solution
A dual-LNA system is implemented, where one LNA acts as a dummy load and the other as a post-amplifier, allowing seamless switching between internal and external configurations by controlling switches and transforming single-ended signals to differential outputs using a load inductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external antenna multiplexer switches are used to switch between internal and external LNA configurations, then configuration flexibility is improved, but device complexity and cost increase
Solution Approach 1:
The second LNA is designed to serve dual purposes: acting as a dummy load when the first LNA is active, and serving as a post-amplifier when an external LNA is connected. This multi-functionality eliminates the need for external antenna multiplexer switches, reducing device complexity while maintaining configuration flexibility between internal and external LNA modes
2Adaptability or versatility
If external antenna multiplexer switches are used to switch between internal and external LNA configurations, then configuration flexibility is improved, but cost increases
Solution Approach 1:
The second LNA performs multiple functions (dummy load and post-amplifier) that would otherwise require separate external components, thereby reducing the bill of materials and manufacturing cost while maintaining the ability to switch between internal and external LNA configurations
3Device complexity
If simple switching between internal and external LNA is implemented, then device complexity is reduced, but performance degradation occurs
Solution Approach 1:
The second LNA acts as an intermediary component that maintains system performance during configuration switching. When the first LNA is active, the second LNA serves as a dummy load to maintain proper impedance matching. When external LNA is used, the second LNA functions as a post-amplifier to maintain signal integrity, thus preventing performance degradation while keeping the switching mechanism simple
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 approach minimizes performance degradation and reduces costs by optimizing signal transmission and reception, eliminating the need for external antenna multiplexer switches and enhancing system gain.
Implementation Method 1
transforming the received single-ended signal to an amplified differential output signal across the first inductor node and the second inductor node
Data Source
AI summary
A load inductor has first and second nodes. The first node couples to a first terminal of a first switch. A second terminal of the first switch couples to an output of a first low noise amplifier (LNA). The second node couples to a third terminal of a second switch. A fourth terminal of the second switch couples to an output of a second LNA. In response to receiving a single-ended signal at the first LNA, the first LNA is turned on, the first switch is closed, the second LNA is turned off, and the second switch is opened. In response to receiving the signal at the second LNA input, the first LNA is turned off, the first switch is opened, the second LNA is turned on, and the second switch is closed. The signal is transformed to a differential signal across the first and second inductor nodes.