GaN Power Amplifier Predistortion for Higher Linear RF Output
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Solution Overview
Problem
Current wireless communication systems face challenges in achieving high linear output power for microwave transmitters due to the inefficiency of GaAs power amplifiers, which are limited by IMD3 levels and require larger devices or multiple modules, leading to increased complexity and cost, and the need for extensive bandwidth matching networks.
Innovation Solution
The implementation of a GaN power amplifier with a predistorter module that detects and corrects distortion, allowing for improved linearity and reduced spectral regrowth, along with an automatic gain adjuster to optimize power levels, resulting in increased output power and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If GaAs power amplifiers are used to achieve high output power, then output power capability is improved, but device complexity and bandwidth matching difficulty increase
Solution Approach 1:
The patent changes the material parameter from GaAs to GaN, which fundamentally alters the power amplifier's characteristics. GaN provides higher output power capability (10 W/mm vs 1 W/mm for GaAs) while operating in Class AB mode enables better efficiency. This material parameter change resolves the contradiction by providing both high power and reduced complexity in bandwidth matching.
Solution Approach 2:
The patent implements an adaptive predistorter that dynamically adjusts its correction parameters based on real-time feedback from the power amplifier's output. This dynamic adaptation allows the system to maintain optimal linearity and efficiency across varying operating conditions and bandwidths, resolving the bandwidth matching complexity issue while preserving high output power capability.
2Power
If multiple power amplifier modules are used in parallel to increase output power, then power capability is improved, but system complexity and component loss increase
Solution Approach 1:
The patent changes the material parameter from GaAs to GaN, which provides inherently higher power density (10 W/mm vs 1 W/mm). This allows a single GaN power amplifier module to replace multiple GaAs modules, reducing system complexity and eliminating the need for multiple couplers, power combiners, and dividers while achieving the same or higher output power.
Solution Approach 2:
The patent extracts and eliminates the unnecessary components (multiple couplers, power combiners, dividers) that are required when using multiple parallel power amplifier modules. By using a single high-power-density GaN module, these intermediate components are removed, reducing system complexity and power loss.
3Power
If power amplifier size is increased to achieve higher output power, then power capability is improved, but bandwidth matching difficulty increases
Solution Approach 1:
The patent changes the material parameter from GaAs to GaN, which provides higher power density without proportionally increasing device size. The GaN HEMT structure enables achieving 10 W/mm power density, allowing high output power with smaller, more manageable device dimensions that are easier to match across bandwidth.
Data Source
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AI summary
Various embodiments provide for systems and methods for increased linear output power of a transmitter. An exemplary wireless communications system for transmitting an input signal comprises a predistorter module, a GaN power amplifier, a coupler, and an antenna. The predistorter module is configured to detect existing distortion by comparing the input signal to a feedback signal and generate a correction signal. The predistorter may adaptively adjust its operation to minimize the existing distortion due to GaN power amplifier nonlinear characteristics. The result is that the GaN power amplifier may send a power signal of improved linearity to the antenna. The coupler is configured to sample the amplified signal from the GaN power amplifier to generate the feedback signal. The antenna is configured to transmit the amplified signal.