Coupled-Line FET Amplifier Matching for Millimeter-Wave Efficiency
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Solution Overview
Problem
Current power amplifiers, particularly those operating at high frequencies, suffer from low efficiency, with Class A, Class AB, and Class B amplifiers achieving less than 35% efficiency above the X band and Class D and Class E designs facing challenges in translating well to these frequencies due to parasitics and impedance control issues.
Innovation Solution
A high efficiency millimeter wave Field-Effect Transistor (FET) amplifier system incorporating a coupled line matching network that matches the output to a power target by configuring the network to match the first and third harmonics and short the second harmonic, thereby improving impedance transformation and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional Class A, Class AB, or Class B amplifiers are used at millimeter wave frequencies, then the amplifier can operate at the desired frequency, but the efficiency remains low (less than 35%)
Solution Approach 1:
The patent changes the impedance parameters at different harmonic frequencies to improve efficiency. The coupled line matching network is designed to present specific impedance values at the fundamental frequency, second harmonic, and third harmonic, transforming the load impedance to achieve optimal operating conditions that maximize power added efficiency to greater than 50%
Solution Approach 2:
The coupled line matching network serves as an intermediary component between the amplifier and the load. This network mediates the impedance transformation and harmonic control, enabling the amplifier to operate at millimeter wave frequencies with high efficiency by controlling the impedance seen by the amplifier at various harmonic frequencies
2Use of energy by moving object
If Class D or Class E amplifier designs are translated to millimeter wave frequencies, then higher efficiency could be achieved, but parasitics and impedance control issues prevent successful implementation
Solution Approach 1:
The matching network is segmented into multiple coupled transmission line sections, each designed to control specific harmonic frequencies. This segmentation allows independent optimization of impedance at the fundamental frequency, second harmonic, and third harmonic, achieving reliable impedance control at millimeter wave frequencies where parasitic effects are significant
Solution Approach 2:
The coupled line matching network performs multiple functions simultaneously: it provides impedance transformation at the fundamental frequency, controls the second harmonic impedance, and controls the third harmonic impedance. This multi-functionality enables high efficiency operation without the reliability issues that plague simplified designs at millimeter wave frequencies
3Use of energy by moving object
If complex matching networks with multiple components are used to achieve impedance transformation, then the efficiency can be improved, but the device size, weight, and complexity increase
Solution Approach 1:
The patent merges multiple matching functions into a single coupled line structure. Instead of using separate components for fundamental frequency matching, second harmonic control, and third harmonic control, the coupled transmission lines perform all these functions simultaneously, reducing device complexity while maintaining greater than 50% efficiency
Solution Approach 2:
The patent uses transmission line theory to solve impedance matching problems in the spatial domain rather than using discrete lumped components. By utilizing the distributed nature of transmission lines and their characteristic impedance properties, the design achieves complex impedance transformations with a compact structure that reduces overall device complexity
4Ease of manufacture
If conventional amplifier designs are used, then the design process is straightforward, but the power added efficiency remains below 35% at Ku and K band frequencies
Solution Approach 1:
The design uses systematic parameter optimization of the coupled line dimensions, spacing, and electrical lengths to achieve the desired impedance transformations. By carefully selecting these geometric parameters, the network achieves greater than 50% power added efficiency while maintaining a design process that is manageable through standard microwave design techniques
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
The system achieves greater than 50% power added efficiency at Ku and K band frequencies, reducing size, weight, and power consumption while providing a scalable and low-loss solution that outperforms traditional amplifier designs.
Implementation Method 1
the matching network is configured for matching an output provided by the amplifier to a power target
Implementation Method 2
matching a first harmonic of the FET amplifier output and a third harmonic of the FET amplifier output to a power target via a coupled line matching network
Implementation Method 3
shorting a second harmonic of the FET amplifier output
Data Source
AI summary
The present invention is a system for providing an optimal power match to an output of an amplifier using a matching network. The system may include a Field-Effect Transistor (FET) amplifier and a load. The system may further include a coupled line matching network connected to and between the FET amplifier and the load. The coupled line matching network may be configured for providing an optimal power match to the FET amplifier in the K band of operation.