Broadband Power Amplifier Matching Network Without Output Transformers
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Solution Overview
Problem
Conventional broadband class-E power amplifiers face challenges in achieving high efficiency and broadband impedance matching to 50 Ohms, often resulting in reduced efficiency and limited bandwidth due to practical issues with reactance compensation networks and sensitivity to parasitic capacitance.
Innovation Solution
The design employs a lumped-element network transform technique, utilizing series and shunt components to create a dual network with equivalent reactance characteristics, applying transforms such as L-left to L-right and L-right to L-left, and using transformers to achieve impedance matching, ultimately resulting in a configuration with no transformers at the output, maintaining high efficiency over a wide frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional reactance compensation networks are used in broadband class-E power amplifiers, then impedance matching can be achieved, but efficiency is reduced and bandwidth is limited due to sensitivity to parasitic capacitance
Solution Approach 1:
The patent transforms the matching network parameters through a series of lumped-element network transforms (L-left to L-right, L-right to L-left) to convert a conventional reactance compensation network into an equivalent network with no transformers at the output. This parameter transformation changes the network's sensitivity characteristics, reducing sensitivity to parasitic capacitance while maintaining impedance matching capability, thereby resolving the contradiction between achieving reliable impedance matching and maintaining high efficiency.
2Reliability
If conventional reactance compensation networks are used in broadband class-E power amplifiers, then impedance matching can be achieved, but bandwidth is limited due to sensitivity to parasitic capacitance
Solution Approach 1:
The patent applies lumped-element network transforms to change the parameters of the matching network, converting it from a transformer-based design to an equivalent design with no output transformers. This parameter change reduces sensitivity to parasitic capacitance effects, thereby extending the operational bandwidth while maintaining reliable impedance matching across the broadband frequency range.
3Reliability
If transformers are used in the matching circuit, then impedance matching can be achieved, but device complexity increases
Solution Approach 1:
The patent extracts and removes transformers from the output side of the matching circuit by applying a sequence of lumped-element network transforms. The transformation process systematically eliminates transformers while maintaining the impedance matching function through equivalent circuit transformations, thereby reducing device complexity and improving reliability by removing potential failure points.
Data Source
AI summary
Matching network for broadband power amplifier. In some embodiments, a power amplifier can include an amplifying transistor having an input and an output, and a matching circuit coupled to the output of the amplifying transistor. The matching circuit can include a first capacitance, an inductance, and a second capacitance connected in series. The matching circuit can further include a third capacitance implemented in a shunt path from a node between the first capacitance and the inductance to a ground, and a fourth capacitance implemented in a shunt path from a node between the inductance and the second capacitance to the ground.