Asymmetric 8-Shaped Inductor Layout for LC-VCO Noise Coupling
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Solution Overview
Problem
Symmetric, 8-shaped inductors in integrated circuits face noise coupling issues, especially when adjacent to a ground top metal, which affects the performance of inductor-capacitor voltage-controlled oscillators (LC-VCOs).
Innovation Solution
An asymmetric, 8-shaped inductor design is implemented, where the inductor is partially surrounded by a ground metal ring and features loops with varying enclosed areas, with the second loop closer to the victim circuit and the first loop farther away, to mitigate noise coupling. This design can be fabricated using conventional semiconductor processes and is applicable to both single and multiple turn inductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If symmetric, 8-shaped inductors are used in integrated circuits, then the inductors can be fabricated using conventional semiconductor processes, but noise coupling issues occur when adjacent to ground top metal affecting LC-VCO performance
Solution Approach 1:
The patent applies asymmetry by designing the inductor with two loops of different sizes (first loop and second loop with different enclosed areas) rather than using a symmetric configuration. This asymmetric structure disrupts the electromagnetic coupling mechanism between the inductor and the ground top metal, thereby reducing noise coupling while maintaining compatibility with conventional semiconductor fabrication processes.
Solution Approach 2:
The patent implements local quality by positioning the loops at different distances from the ground top metal (first loop farther away, second loop closer) and giving them different enclosed areas. This creates non-uniform electromagnetic field distribution locally, which mitigates the noise coupling effect from the ground top metal while preserving the overall inductor functionality.
2Object-affected harmful factors
If the inductor is surrounded by ground metal ring, then electromagnetic interference is mitigated, but the complexity of the device structure increases
Solution Approach 1:
The patent employs an asymmetric inductor structure with loops of different sizes and positions, which inherently provides electromagnetic interference mitigation without requiring an additional ground metal ring. The asymmetric configuration itself creates a more favorable electromagnetic environment, reducing the need for extra shielding structures and thereby avoiding increased device complexity.
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 asymmetric, 8-shaped inductor achieves a 20 dB reduction in noise coupling, enhancing electrical performance in voltage-controlled oscillators by reducing electromagnetic interference.
Implementation Method 1
providing current to the inductors in a way so that the resulting magnetic field components tend to cancel each other by virtue of the symmetry
Implementation Method 2
the inductor is at least partially surrounded by a ground metal ring
Data Source
AI summary
A semiconductor device includes a substrate; a first terminal and a second terminal; and a conductor arranged on the substrate between the first terminal and the second terminal to constitute an inductor shaped for forming a first loop and a second loop. A first crossing of the conductor with itself is present between the first loop and the second loop. The first loop and the second loop define a first enclosed area and a second enclosed area, respectively. The first enclosed area is smaller than the second enclosed area.