Quarter-Wave Harmonic Circuit Layout for Low-Stray-Capacitance Amplifiers
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Solution Overview
Problem
Amplifiers using harmonic processing circuits suffer from deterioration in characteristics such as reduced frequency bandwidth and decreased power added efficiency due to stray capacitance and loss, particularly when using open stubs for harmonic shorting.
Innovation Solution
A harmonic processing circuit design utilizing two parallel wires with a dielectric film in between, where each wire is ¼ wavelength of a harmonic and half the width of a single open stub, effectively shorting harmonics while minimizing stray capacitance and loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single open stub is used for harmonic shorting, then the harmonic shorting function is achieved, but stray capacitance and loss increase causing deterioration in amplifier characteristics
Solution Approach 1:
The single open stub is divided into two separate wires (first wire and second wire) that are parallel to each other. Each wire has a length of 1/4 wavelength of the harmonic to be shorted. By segmenting the original structure, the patent reduces stray capacitance and loss while maintaining the harmonic shorting function, thereby improving amplifier characteristics.
2Loss of energy
If the width of the open stub is reduced to minimize stray capacitance, then stray capacitance decreases, but the harmonic shorting effectiveness is compromised
Solution Approach 1:
Instead of reducing the width of a single stub, the patent transitions to a two-wire configuration where each wire has optimal dimensions. The wires are arranged parallel to each other with specific spacing, creating a new dimensional arrangement that achieves both low stray capacitance and effective harmonic shorting. The length of each wire is set to 1/4 wavelength of the harmonic frequency.
3Reliability
If a wider open stub is used, then harmonic shorting effectiveness is improved, but stray capacitance and loss increase reducing frequency bandwidth and power added efficiency
Solution Approach 1:
The patent segments the wide single stub into two narrower parallel wires, each with length of 1/4 wavelength of the harmonic. This segmentation maintains the harmonic shorting effectiveness through the combined effect of the two wires while reducing the overall stray capacitance and loss, thereby preserving frequency bandwidth and power added efficiency.
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 design enhances amplifier performance by suppressing harmonic influence on the fundamental wave, reducing stray capacitance, and maintaining high power efficiency and frequency bandwidth.
Implementation Method 1
a first wire configured to have a first end connected to the transmission line and a second end opened, a length between the first end and the second end being 1/4 wavelength of a predetermined harmonic with respect to the fundamental wave; a second wire configured to be parallel to and apart from the first wire, and have both ends opened, a length between the both ends being 1/4 wavelength of the predetermined harmonic
Data Source
AI summary
A harmonic processing circuit includes a transmission line for transmitting the fundamental wave, a first wire connected to the transmission line, a second wire provided parallel to and apart from the first wire, and a dielectric film interposed between the first wire and the second wire. The first wire has a first end connected to the transmission line and a second end opened. The length between the first end and the second end of the first wire is set to ¼ wavelength of a predetermined harmonic with respect to the fundamental wave. The second wire has both first and second ends opened. The length between the first end and the second end of the second wire is set to ¼ wavelength of the predetermined harmonic.