Inductor Gain Lead Structure for RF Q-Factor
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Solution Overview
Problem
In integrated circuits, inductors face challenges due to conductor thickness limitations and interference from silicon substrates, which degrade their quality factor (Q-factor) and increase parasitic capacitance, limiting their effectiveness in RF applications.
Innovation Solution
The inductor structure incorporates a gain lead disposed under the grounded coil turn, electrically connected in parallel, with a width less than the coil turn, to increase the conductor section area and reduce parasitic capacitance, thereby enhancing the inductor's quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a thicker metal element is disposed at the uppermost layer of the inductor to reduce conductor loss, then the Q-factor is improved, but the improvement becomes not notable when the metal thickness is increased to a certain degree
Solution Approach 1:
The patent transitions from increasing thickness (vertical dimension) to increasing width (horizontal dimension) of the conductor. Instead of making the uppermost metal layer thicker, the invention adds a gain lead extending in the horizontal plane beneath the coil, thereby increasing the effective conductor cross-sectional area without increasing vertical thickness, resolving the diminishing returns of thickness increase.
Solution Approach 2:
The gain lead is disposed beneath the coil structure, nesting the additional conductor within the existing vertical space. This allows the effective conductor area to be increased by utilizing the space underneath the coil rather than adding more vertical layers, thus improving current carrying capacity without increasing overall structure height.
2Loss of energy
If a gain lead is disposed under the grounded coil turn to increase conductor section area, then conductor loss is reduced, but parasitic capacitance is increased which negatively affects inductance quality
Solution Approach 1:
The gain lead is positioned specifically under the grounded coil turn where it provides benefit without excessive parasitic effect. The width of the gain lead is controlled to be less than the width of the coil turn, creating a localized conductor enhancement rather than a broad area connection, thus balancing conductor loss reduction with parasitic capacitance control.
3Loss of energy
If the width of the gain lead is increased to further reduce conductor loss, then the conductor section area is increased, but the parasitic capacitance caused by coupling between the gain lead and the substrate increases
Solution Approach 1:
The patent optimizes the width parameter of the gain lead, setting it to be less than the width of the coil turn. This parameter optimization balances two competing effects: sufficient width to provide meaningful conductor loss reduction, but limited width to control parasitic capacitance to acceptable levels.
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 configuration effectively reduces conductor loss and improves the inductor's quality by increasing the conductor section area and minimizing parasitic capacitance, leading to better performance in RF circuits.
Implementation Method 1
increase the section area of conductor in the inductor structure which is able to effectively lower conductor loss
Implementation Method 2
the parasitic capacitance caused by the coupling between the gain lead and the substrate of the inductor structure
Data Source
AI summary
An inductor structure including a coil layer and at least a gain lead is disclosed. The coil layer is disposed over a substrate and has a plurality of coil turns, wherein one of the coil turns is grounded. The gain lead is disposed under at least one of the inner side and the outer side of the grounded coil turn and is electrically connected in parallel to the grounded coil turn. The width of the gain lead is less than the width of the grounded coil turn.