Variable Inductance Spiral Inductor with Segmented Conductors
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Solution Overview
Problem
Conventional spiral inductors in high-frequency communication devices face challenges in controlling inductance values effectively, leading to decreased integration and quality factor due to increased parasitic capacitance, and are unable to achieve maximum Q-factor across desired frequency bands.
Innovation Solution
A spiral inductor design featuring conductors of different widths with open or short-type stubs and switching means allows for precise control of inductance by inducing parasitic capacitance or inductance, enabling various inductance values and high Q-factor across a high frequency band using a small substrate area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the number of turns, inner diameter, or metal line width of the spiral conductor is increased to increase inductance, then the whole inductance increases, but the area occupied by the inductor increases and parasitic capacitance increases, causing the Q-factor to decrease
Solution Approach 1:
The spiral conductor is divided into multiple sections with different metal line widths. Each section contributes differently to the total inductance, allowing precise control of the inductance value without proportionally increasing the overall area. The segmented structure enables selective activation of conductor segments to achieve desired inductance values.
Solution Approach 2:
Different sections of the spiral conductor have different local properties (different metal line widths). Wider sections provide higher inductance per turn, while narrower sections provide lower inductance. This local variation in quality allows the inductor to achieve a range of inductance values within a compact area by selectively connecting sections with different widths.
2Extent of automation
If the inductor area is increased to achieve a predetermined inductance value, then the inductance increases, but parasitic capacitance between ports and substrate increases, causing Q-factor to rapidly decrease
Solution Approach 1:
The conductor is segmented into sections with different widths, allowing the inductance to be adjusted by connecting specific segments rather than uniformly increasing the entire conductor width. This segmentation enables achieving the required inductance value with minimal necessary area, thereby minimizing parasitic capacitance to the substrate.
Solution Approach 2:
The metal line width parameter is varied across different sections of the spiral conductor. By changing this parameter locally rather than uniformly, the inductor can achieve variable inductance values without proportionally increasing the area and parasitic capacitance. Switching means are used to select which width parameter is active for a given operating condition.
3Ease of manufacture
If the spiral conductor uses uniform metal line width, then the structure is simple, but the inductance value cannot be accurately controlled for specific frequency bands
Solution Approach 1:
The uniform conductor structure is segmented into sections with different metal line widths. While this increases manufacturing complexity slightly, it enables precise control of the inductance value by selectively connecting sections with specific width characteristics. The segmentation allows the inductor to be tuned for specific frequency bands by activating appropriate conductor sections.
Solution Approach 2:
The conductor structure transitions from a static uniform width design to a dynamic configuration where different width sections can be selectively connected or disconnected. This dynamic reconfiguration capability allows the inductor to adapt its inductance value for different frequency bands, achieving precise control while maintaining relatively simple manufacturing processes.
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 design allows for accurate control of inductance values and enhanced Q-factor across specific frequency bands, increasing the degree of integration in communication devices while maintaining a compact footprint.
Implementation Method 1
open or short-type stubs are formed at one side of each of the conductors to induce parasitic capacitances or inductances
Data Source
AI summary
Disclosed is a spiral inductor formed on a semiconductor substrate. The spiral inductor comprises: a metal line forming a spiral pattern on a substrate using conductors having different widths and having open or short-type stubs at one side of each of the conductors; and switching means connection-controlled in accordance with a selection signal for adjusting an inductance and selectively connecting the conductors of the different widths of the metal line. According to the invention, the open or short-type stubs may be formed at one sides of each of the conductors, thereby inducing a parasitic capacitance or parasitic inductance. Based on the inducement of the parasitic capacitance or inductance and selectively connection of the conductors to one another through switching means, it is possible to accurately control a whole inductance value of the spiral inductor, depending on use purposes.