Non-Integer Turn-Ratio Inductors in ICs
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Solution Overview
Problem
Existing RF inductors in integrated circuits (ICs) have limited, integer-based turn-ratios, which are insufficient for recent RFIC design requirements, and occupy a larger footprint, limiting their implementation in compact IC designs.
Innovation Solution
A pair of inductors with a non-integer turn-ratio is implemented, where the secondary inductor is formed on a different layer with a greater length than the primary inductor, allowing for fine-tuning of the transient gap fraction to achieve desired turn-ratios, such as 1:m, while maintaining high mutual inductance and low insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing RF inductors with integer-based turn-ratios are used, then the device structure is simple and easy to manufacture, but the adaptability for different RFIC design requirements is limited
Solution Approach 1:
The patent introduces a new dimension by placing inductors on different layers of the IC substrate. The primary inductor is on a first layer while the secondary inductor is on a second layer, enabling three-dimensional spatial arrangement. This layer separation allows for non-integer turn-ratios to be achieved through controlled coupling between layers, rather than requiring complex planar configurations on a single layer.
Solution Approach 2:
The patent changes the turn-ratio parameter from integer-based to non-integer-based by controlling the coupling between primary and secondary inductors. The turn-ratio is determined by the ratio of effective lengths (Le1 and Le2) of the inductors, which can be continuously adjusted by modifying the physical dimensions and spacing between layers, enabling precise control of the turn-ratio parameter for different design requirements.
2Area of stationary object
If inductors are placed on different layers with greater secondary length, then non-integer turn-ratios are achieved and area usage is improved, but the device structure becomes more complex
Solution Approach 1:
The patent implements a nested structure where the secondary inductor on the second layer is positioned to overlap with the primary inductor on the first layer. The secondary inductor's conductive traces are arranged to be substantially contained within the footprint of the primary inductor, creating a nested configuration that maximizes area utilization while maintaining electromagnetic coupling between layers.
Solution Approach 2:
By transitioning from a two-dimensional planar arrangement to a three-dimensional multi-layer structure, the patent achieves better area utilization. The vertical stacking of inductors on different layers allows the secondary inductor to have a greater effective length without increasing the horizontal footprint, thereby achieving non-integer turn-ratios within a compact area.
3Manufacturing precision
If the secondary inductor length is increased for non-integer turn-ratios, then the turn-ratio precision is improved, but the inductor footprint increases
Solution Approach 1:
The patent resolves the area-precision contradiction by extending the secondary inductor length in the vertical dimension through multi-layer stacking rather than in the horizontal dimension. The effective length Le2 is increased by utilizing multiple turns on the second layer, while the horizontal footprint is constrained by positioning these turns within the same planar envelope as the primary inductor on the first layer.
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 enables flexible turn-ratio tuning, improved impedance transformation, and enhanced area usage on ICs, supporting advanced RFIC designs with unconventional turn-ratios within a limited footprint.
Implementation Method 1
An inductor, which usually takes the form of a coil, is an electrical and electronic component that stores energy in a magnetic field when an electric current flows through it
Data Source
AI summary
Embodiments described herein provide circuitry employing one or more inductors having an unconventional turn-ratio. The circuitry includes a primary inductor having a first length located on a first layer of an integrated circuit (IC). The circuitry further includes a secondary inductor having a second length located on a second layer of the IC different from the first layer, whereby the second length is greater than the first length, with a ratio between the first and the second lengths corresponding to a non-integer turn-ratio.