Doherty Amplifier Output Line Layout for Precise Band Tuning
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Solution Overview
Problem
Existing Doherty amplifiers require additional components and complex adjustments to change the frequency band for high power efficiency, leading to potential size increases and restricted adjustment accuracy of output impedance.
Innovation Solution
A Doherty amplifier design that includes a first output transmission line with a wide portion, allowing for precise adjustment of the output impedance of the carrier amplifier by varying the width of only this portion, thereby enhancing the adjustment range and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the width of the whole first output transmission line is adjusted to change output impedance, then the frequency band for high power efficiency can be changed, but the adjustment range is limited by processing accuracy of the transmission line width
Solution Approach 1:
The first output transmission line is divided into a narrow portion and a wide portion with different widths. By adjusting only the width of the wide portion while keeping the narrow portion fixed, the patent achieves both a larger adjustment range and maintained processing accuracy. The segmentation allows independent optimization of each section's function.
Solution Approach 2:
The patent applies local quality by making different portions of the transmission line have different widths. The wide portion is specifically designed with a larger width to provide sufficient adjustment range, while the narrow portion maintains the original dimensions. This local differentiation enables the system to overcome the limitation of uniform width adjustment.
2Adaptability or versatility
If additional second amplifiers and switch units are added to change frequency band, then the frequency band for high power efficiency can be adjusted, but the device size becomes larger
Solution Approach 1:
The patent changes the physical parameter (width) of the existing first output transmission line to achieve frequency band adjustment. By modifying the width of the wide portion, the impedance transformation ratio changes, enabling frequency band adjustment without adding new amplifiers or switch units. This parameter-based approach maintains device compactness.
Solution Approach 2:
The first output transmission line is designed to serve multiple functions: it acts as both a carrier amplifier output line and provides impedance transformation for frequency band adjustment. The wide portion specifically enables this multi-functionality by providing both signal transmission and impedance tuning capabilities, eliminating the need for separate adjustment components.
Data Source
AI summary
A Doherty amplifier according to the disclosure includes an input terminal, a first input transmission line connected to the input terminal via a branch portion, a second input transmission line connected to the input terminal via the branch portion, a carrier amplifier connected to the first input transmission line, a peak amplifier connected to the second input transmission line, a first output transmission line including one end connected to output of the carrier amplifier, a second output transmission line including one end connected to output of the peak amplifier, a synthesis line including one end connected to another end of the first output transmission line and another end of the second output transmission line and an output terminal connected to another end of the synthesis line, wherein the first output transmission line includes a wide portion which is wider than another portion of the first output transmission line.