Non-Uniform Distributed Power Amplifier for Multi-Octave Bandwidth
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Solution Overview
Problem
Existing solid-state microwave power amplifiers face limitations in achieving multi-octave frequency bandwidths due to issues with traveling wave tubes, such as unreliability, high voltage requirements, and parasitic capacitance, which restrict power and frequency range, and conventional uniformly distributed amplifiers suffer from suboptimal loading and parasitic problems.
Innovation Solution
The use of non-uniformly distributed amplifier strings with real input and output impedances, allowing for modular replication and connection using simple impedance transformers, eliminates the need for drain line termination and parasitic capacitance absorption, enabling ultra-wide bandwidth and flat power output across multiple octaves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traveling wave tubes are used to achieve high-power microwave output, then power output is improved, but reliability deteriorates and device complexity increases
Solution Approach 1:
The amplifier is divided into multiple distributed unit cells, each contributing to the overall power output. Instead of relying on a single traveling wave tube, the patent uses many small solid-state amplifier cells distributed along transmission lines, where each cell operates independently but contributes to the aggregate power output, thereby improving reliability through distribution.
Solution Approach 2:
The patent replaces the mechanical/electromagnetic traveling wave tube system with a solid-state electronic system. The traveling wave tube, which relies on electron beam interaction with electromagnetic fields, is substituted with solid-state transistor-based amplifier cells, eliminating the need for high-voltage power supplies and improving reliability while maintaining high-power output capability.
2Power
If traveling wave tubes are used to achieve high-power microwave output, then power output is improved, but device complexity and high-voltage requirements increase
Solution Approach 1:
The patent extracts and eliminates the high-voltage supply requirement from the system. By replacing traveling wave tubes with solid-state amplifier cells, the complex high-voltage power supply infrastructure is removed entirely, simplifying the overall device architecture while maintaining the ability to generate high-power microwave signals through parallel operation of multiple low-voltage solid-state devices.
3Adaptability or versatility
If conventional uniformly distributed amplifiers are used to increase bandwidth, then frequency range is improved, but parasitic capacitance and suboptimal loading reduce power output
Solution Approach 1:
The patent applies local quality by making each distributed unit cell identical in structure but optimizing the local impedance transformation ratios to account for the cumulative effect of parasitic capacitances. Each cell is designed with specific gate and drain line characteristic impedances that are tailored to its position in the distribution, ensuring that all cells operate at optimal power levels across the entire frequency bandwidth despite the presence of parasitic effects.
4Power
If larger active devices are used to increase power output, then power per device is improved, but parasitic capacitance increases and bandwidth decreases
Solution Approach 1:
Instead of using a single large active device with high power output capability but limited bandwidth due to parasitic capacitance, the patent segments the total power requirement into multiple smaller active devices. Each small device operates within its optimal frequency range with minimal parasitic effects, and the aggregate power output of all devices combined achieves the desired high-power level while maintaining ultra-wide bandwidth coverage from 2 GHz to 18 GHz and beyond.
Data Source
AI summary
A number of identical non-uniformly distributed ultra-wideband power amplifier string building blocks are coupled together to form an ultra-wide bandwidth high-power amplifier. The non-uniform distribution results in an amplifier utilizing modular string building blocks that have input and output impedances with only real values. This permits the strings to be replicated and connected together with simple impedance matching. The internal impedance matching associated with the non-linear distribution also absorbs parasitic capacitance to permit the ultra-broadband operation. In one embodiment identical transistors are used for each cell so that the strings may be identically replicated. This permits modular re-use without reconfiguration. In one embodiment a non-uniform distributed power amplifier built using the subject building blocks provides an ultra-wideband multi-octave device suitable for electronic warfare and communications applications, especially to replace traveling wave tubes.