Multi-turn Inductor Parasitic Capacitance Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multi-turn inductors, such as two-turn inductors, often suffer from imbalance due to the use of underpass metal traces and vias, which can degrade the performance of application circuits by deteriorating second-order distortion in amplifiers.
Innovation Solution
A multi-layer structure is implemented with a multi-turn coil divided into two halves, where additional metal is added beneath the half with greater parasitic capacitance to balance the parasitic capacitance, ensuring balanced current flow between the ends and the center tap, thereby offsetting the imbalance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an underpass metal trace is used to connect multiple turns in a multi-layer structure, then the inductor can be constructed with multiple turns, but the inductor becomes unbalanced due to parasitic capacitance
Solution Approach 1:
The patent applies local quality by adding compensation metal traces specifically beneath the turn with less parasitic capacitance. This creates a non-uniform distribution of parasitic capacitance that intentionally compensates for the inherent imbalance, allowing each local region to have different capacitance characteristics to achieve overall balance.
Solution Approach 2:
The patent introduces asymmetry by deliberately adding compensation metal only on one side (beneath specific turns) rather than uniformly distributing metal throughout. This asymmetric structure creates intentional parasitic capacitance differences that counterbalance the inherent asymmetry in the underpass trace configuration.
2Stability of the object's composition
If additional metal is added to compensate for parasitic capacitance imbalance, then the balance of the inductor is improved, but the device complexity increases
Solution Approach 1:
The patent merges the compensation function with the existing multi-layer metal structure by integrating compensation metal traces into the same layer system. Rather than adding a separate compensation structure, the solution combines the inductive elements and compensation elements into a unified multi-layer architecture.
3Ease of manufacture
If the inductor is made unbalanced by using underpass traces, then fabrication is simplified, but the performance of application circuits deteriorates due to second-order distortion
Solution Approach 1:
The patent applies preliminary anti-action by pre-compensating for the expected performance degradation during the fabrication process. The compensation metal traces are designed and placed beforehand to counteract the harmful effects of the underpass trace configuration before the inductor is actually used in a circuit, thereby preventing second-order distortion issues.
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 approach results in a more balanced frequency response of the inductor, improving the performance of application circuits by reducing second-order distortion.
Implementation Method 1
additional metal is laid out beneath the first half only if the second half has a greater parasitic capacitance, and the additional metal layer is laid out beneath the second half only if the first half has a greater parasitic capacitance
Data Source
AI summary
An inductor is laid out on a multi-layer structure, the inductor having a multi-turn coil including a plurality of metal traces laid out on at least two metal layers and a plurality of vias configured to provide inter-layer connection, wherein the multi-turn coil includes a first half configured to conduct a current flow between a first end and a center tap and a second half configured to conduct a current flow between a second end and the center tap; and an additional metal laid out on a metal layer below a lowest metal layer of the multi-turn coil, wherein the additional metal is laid out beneath the first half if the second half has a greater parasitic capacitance, or alternatively beneath the second half if the first half has a greater parasitic capacitance.