Ground Plane Height Variation for Doherty Amplifier Footprint
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Solution Overview
Problem
Conventional Doherty amplifier modules face challenges in fitting different power levels within a compact footprint due to varying characteristic impedance requirements, leading to difficulties in accommodating higher power level designs within the space allocated for lower power levels.
Innovation Solution
A Doherty amplifier module with a multi-layer substrate incorporating a ground plane height variation structure, which effectively reduces the distance between the inverter line and the system ground plane, allowing for similar width inverter lines with different characteristic impedances, enabling modules of various power levels to share the same footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different characteristic impedance transmission lines are used for different power levels, then each power level achieves optimal performance, but the physical width varies widely making it impossible to fit higher power designs within the space allocated for lower power designs
Solution Approach 1:
The patent introduces a vertical dimension by varying the ground plane height underneath the transmission line. Instead of changing only the horizontal width to achieve different characteristic impedances, the design modifies the vertical distance between the transmission line and the ground plane. This allows different power level designs to use transmission lines of similar width while achieving different characteristic impedances through varying ground plane heights, enabling them to fit within the same footprint.
Solution Approach 2:
The patent applies local quality by creating regions with different ground plane heights in different zones of the substrate. Specifically, a first zone has a first ground plane height for lower power levels, while a second zone has a second ground plane height for higher power levels. This localized variation in ground plane height allows each power level to achieve its optimal characteristic impedance while maintaining a compact overall footprint.
2Area of stationary object
If the transmission line width is reduced to fit higher power designs in the same space, then the footprint is maintained, but the characteristic impedance cannot be properly adjusted for different power levels
Solution Approach 1:
The patent adds a vertical degree of freedom by varying ground plane height. This allows the characteristic impedance to be adjusted for different power levels without changing the transmission line width, thereby maintaining adaptability while keeping the footprint compact.
Solution Approach 2:
The patent changes the physical parameter of ground plane height to achieve different characteristic impedances. By modifying this geometric parameter vertically rather than horizontally, the design maintains transmission line width while achieving the necessary impedance variations for different power levels.
3Area of stationary object
If the ground plane height is varied to achieve different characteristic impedances, then compact footprint is achieved, but the manufacturing complexity increases
Solution Approach 1:
The patent segments the ground plane into multiple zones with different heights. The substrate is divided into a first zone and a second zone, each with its own ground plane height optimized for specific power levels. This segmentation allows standard manufacturing processes to be applied to each zone independently, reducing overall manufacturing complexity while achieving the compact footprint benefit.
Data Source
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AI summary
An embodiment of a module (e.g., an amplifier module) includes a substrate, a transmission line, and a ground plane height variation structure. The substrate is formed from a plurality of dielectric material layers, and has a mounting surface and a second surface opposite the mounting surface. A plurality of non-overlapping zones is defined at the mounting surface. The transmission line is coupled to the substrate and is located within a first zone of the plurality of non-overlapping zones. The ground plane height variation structure extends from the second surface into the substrate within the first zone. The ground plane height variation structure underlies the transmission line, a portion of the substrate is present between the upper boundary and the transmission line, and the ground plane height variation structure includes a conductive path between an upper boundary of the ground plane height variation structure and the second surface.