Class-F PA Matching Network With Lumped Harmonic Traps
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Solution Overview
Problem
Designing a class-F power amplifier (PA) that efficiently amplifies radio frequency (RF) signals for multiband applications in portable devices is challenging due to the complexity of impedance matching at multiple harmonic frequencies, and existing solutions using transmission lines are costly and increase the device footprint.
Innovation Solution
A class-F PA with a matching network and a second harmonic trap circuit implemented using lumped inductive and capacitive components, which selectively attenuates impedance at specific harmonic frequencies without the need for transmission lines, allowing for independent control of common mode and differential mode impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmission lines are used for impedance matching at multiple harmonic frequencies, then impedance matching performance is improved, but device footprint and cost increase
Solution Approach 1:
The patent replaces transmission line-based impedance matching networks with lumped element circuits (inductors and capacitors). This substitution eliminates the need for long transmission lines while achieving the same impedance matching function at multiple harmonic frequencies, thereby reducing device footprint without sacrificing matching performance.
Solution Approach 2:
The patent uses variable lumped elements (inductors and capacitors) with specific impedance values to achieve impedance matching at multiple harmonic frequencies. By carefully selecting and tuning the parameters of these lumped elements, the circuit can provide the required impedance transformation without the physical constraints of transmission lines.
2Reliability
If transmission lines are used for impedance matching at multiple harmonic frequencies, then impedance matching performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive transmission line implementations with simpler lumped element circuits. Lumped inductors and capacitors are generally more cost-effective to manufacture and integrate, especially in multiband applications where multiple transmission lines would be required for different frequency bands.
Solution Approach 2:
The lumped element circuit is designed to provide impedance matching across multiple harmonic frequencies simultaneously. This multi-functional approach eliminates the need for separate transmission line networks for each frequency band, reducing overall component count and manufacturing complexity.
3Power
If class-F PA with multiple harmonic frequencies is implemented, then power amplification capability is improved, but circuit complexity increases
Solution Approach 1:
The patent combines the functions of multiple impedance matching networks (one for each harmonic frequency) into a single integrated lumped element circuit. This merging of functions maintains the power amplification capability across multiple harmonics while reducing the overall circuit complexity compared to having separate matching networks for each frequency.
Solution Approach 2:
The patent uses a unified lumped element circuit with carefully selected component values to handle multiple harmonic frequencies. By changing the approach from frequency-specific transmission lines to a parameter-tuned lumped element network, the circuit complexity is reduced while maintaining the ability to amplify multiple harmonics effectively.
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 approach enables simultaneous impedance matching for the first three harmonics, reducing power consumption and increasing efficiency while minimizing device size and cost, and is suitable for low-cost, high-integration semiconductor fabrication.
Implementation Method 1
The second harmonic trap circuitry comprises a plurality of lumped inductive and capacitive components configured to resonate at the second harmonic frequency (fH2) and provide a short circuit path for the second harmonic signal while blocking the third harmonic signal
Implementation Method 2
The matching network is configured to match the impedance between the pair of differential output terminals and the load resistance, enabling maximum power transfer from the power amplifier to the load at the fundamental frequency (fH1)
Data Source
AI summary
A class-F power amplifier (PA) with a matching network is disclosed herein. The class-F PA comprises a first switch and a second switch operating in differential mode, with a second harmonic trap circuitry selectively terminating the drain terminals to ground at a second harmonic frequency. The second harmonic trap circuitry comprises a plurality of lumped inductive and capacitive components. The PA further comprises a common mode trap and a matching network to reduce the imbalance of the drain terminal impedance between first harmonics and third harmonics.