GaN Doherty Amplifier With Split Epitaxy for Power Density
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Solution Overview
Problem
Traditional Doherty amplifiers constructed using the same epitaxial structure for both main and peaking amplifiers can lead to variations and limitations in performance, requiring innovative approaches to enhance power density, gain, transconductance, and thermal management.
Innovation Solution
The use of Doherty amplifiers with main and peaking amplifiers having different epitaxial structures, specifically from different Group III nitride epiwafers, allowing for varied properties such as higher power density, gain, transconductance, and linear amplification, while differing in polarity and potentially including dielectric interlayers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the same epitaxial structure is used for both main and peaking amplifiers, then manufacturing consistency is improved, but performance optimization and power density are limited
Solution Approach 1:
The patent applies local quality by using different epitaxial structures for the main amplifier and peaking amplifier. The main amplifier uses a first epitaxial structure optimized for linear amplification, while the peaking amplifier uses a second epitaxial structure optimized for high power density. This allows each amplifier to have locally optimized properties tailored to its specific function within the Doherty configuration.
2Power
If different epitaxial structures are used for main and peaking amplifiers, then power density and gain are improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the amplifier system into two distinct parts with different epitaxial structures. The main amplifier and peaking amplifier are separated and each uses an epitaxial structure specifically optimized for its function. This segmentation allows independent optimization of each amplifier's performance characteristics while maintaining overall system functionality.
3Reliability
If higher Al content is used in AlGaN barrier layer, then electron mobility and transconductance are improved, but breakdown voltage decreases
Solution Approach 1:
The patent applies parameter changes by varying the aluminum content in the AlGaN barrier layer between 20-40% for the main amplifier and 30-50% for the peaking amplifier. This parameter optimization allows the main amplifier to achieve high transconductance with moderate Al content, while the peaking amplifier uses higher Al content to maximize electron mobility and power density, with each structure's parameters tailored to its operational requirements.
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 configuration enables improved performance by optimizing power density, gain, and thermal management, reducing material requirements and manufacturing costs, and achieving efficient operation across a range of input signal powers.
Implementation Method 1
the Al content in the AlGaN layer creates a piezoelectric charge at the interface, transferring electrons to the 2DEG in the GaN layer
Implementation Method 2
a heterojunction is formed at the boundary of layers of GaN and, e.g., AlGaN. As used herein, AlGaN is an abbreviation for the formula AlxGa1-xN
Data Source
AI summary
A Doherty amplifier comprises a main amplifier and a peaking amplifier. The main amplifier and the peaking amplifier are electrically connected to a same input signal source. The main amplifier and the peaking amplifier comprise different epitaxial structures of a Group III nitride material. To form the Doherty amplifier, the main amplifier and the peaking amplifier are formed comprising Group III nitride transistors comprising different epitaxial structures from different epiwafers such that the Group III nitride transistors of the main and peaking amplifiers comprise different epitaxial structures. The wafers are diced to produce respective amplifier dies comprising the main amplifier and peaking amplifier, respectively. The amplifier dies are mounted on a common heat sink, and the main and peaking amplifiers are electrically connected to the input signal source.