Low-Noise Amplifier Impedance Matching for Carrier Aggregation
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Solution Overview
Problem
Low noise amplifiers (LNAs) in wireless communication devices face challenges in maintaining uniform input impedance across various operation modes, especially when supporting multiple frequency channels through carrier aggregation, leading to increased area requirements and reduced efficiency due to the need for separate source degeneration inductors for each carrier component.
Innovation Solution
The design incorporates a low noise amplifier with multiple amplifier stages and cascode transistors, where the first type gain stage includes an input transistor and a degeneration inductor, and the second type gain stage includes a cascode transistor, allowing for adjustable impedance to maintain uniform input impedance regardless of operation mode, and reduces the number of degeneration inductors by sharing them between stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate source degeneration inductors are used for each carrier component to support multiple frequency channels, then the LNA can maintain proper impedance matching for each carrier, but the device area increases and efficiency decreases
Solution Approach 1:
The patent combines multiple source degeneration inductors into a single shared inductor that serves multiple carrier components. This is achieved by configuring the inductor network such that one inductor (L1) is shared between first and second carrier components, while another inductor (L2) is shared between third and fourth carrier components. This merging approach reduces the total number of inductors required, thereby decreasing device area while maintaining the ability to support multiple frequency channels through selective activation of different inductor configurations.
Solution Approach 2:
The shared source degeneration inductors are designed to serve multiple functions across different carrier components. The same inductor L1 provides impedance matching for both first and second carrier components, and inductor L2 serves third and fourth carrier components. This multi-functionality allows a single inductor to replace what would traditionally require separate dedicated inductors for each carrier, reducing overall component count and device area while maintaining adaptability to multiple frequency channels.
2Productivity
If the LNA is designed to support variously arranged frequency channels through carrier aggregation, then communication efficiency improves, but maintaining uniform input impedance across different operation modes becomes difficult
Solution Approach 1:
The patent implements dynamic impedance matching by selectively activating different inductor configurations based on the operating mode and carrier aggregation configuration. Switches control the connection of inductors L1 and L2 to different nodes depending on which carrier components are active. This dynamic reconfiguration allows the input impedance to be optimized and maintained uniformly across different operation modes, whether single-carrier or multi-carrier aggregation, by adapting the impedance network to the current operational requirements.
Solution Approach 2:
The patent changes the effective impedance parameters of the input network by reconfiguring the inductor connections. By switching between different inductor configurations (e.g., connecting L1 to different nodes or bypassing it entirely), the overall input impedance is adjusted to maintain uniformity across various operation modes. This parameter change approach allows the same physical inductors to provide different impedance values suitable for different carrier aggregation scenarios, thereby maintaining input impedance uniformity while supporting diverse frequency channel arrangements.
3Adaptability or versatility
If multiple amplifier stages with different transistor types are used to support various operation modes, then the LNA becomes more versatile, but the device complexity increases
Solution Approach 1:
The patent segments the amplifier into distinct functional stages: a first amplifier stage with a first type gain stage and first type drive stages, and second and third amplifier stages with second type gain stages and second type drive stages. Each stage is optimized for specific operation modes. The first amplifier stage handles certain carrier components while the second and third stages handle others. This segmentation allows each stage to be independently optimized and controlled, reducing the complexity of managing a fully integrated multi-mode amplifier while maintaining versatility through selective stage activation.
Solution Approach 2:
The patent introduces intermediate drive stages between the gain stages and output stages, with each drive stage containing cascode transistors that act as intermediaries. These drive stages buffer and adapt the signals between different amplifier stages, allowing the first type and second type gain stages to operate independently without direct interference. This intermediary structure simplifies the overall design by providing clear functional boundaries between stages while enabling versatile operation mode support through selective activation of different stage combinations.
Data Source
AI summary
Provided are a low noise amplifier and a receiver. The low noise amplifier comprises at least one input port configured to receive an input signal including a carrier, first to third output ports connected to first to third load circuits, respectively, and configured to transmit an output signal, a first amplifier stage comprising a first type gain stage connected to the input port and first to third first type drive stages connected to the first to third output ports, respectively and second to third amplifier stages, each comprising a second type gain stage and a second type drive stage, wherein the low noise amplifier is configured to vary an impedance of an input transistor included in each of the first type gain stage and the second type gain stage, so that an input impedance is uniform even when operating in a plurality of operation modes.