Figure-of-Eight Inductor Structure for IC Area Reduction

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Solution Overview

Problem

Integrated circuits with multiple inductors face challenges in minimizing chip area while maintaining performance due to magnetic coupling, and existing designs that embed one inductor within another lack the ability to operate inductors independently or as a composite without compromising area efficiency.

Innovation Solution

A dual-band inductor structure comprising a first inductor coil with a figure-of-eight configuration and a second multi-turn loop surrounding it, where the central terminal connects the coils and allows for independent or concurrent operation, effectively canceling out electromagnetic fields and reducing mutual coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If inductors are physically separated to reduce magnetic coupling, then magnetic coupling between inductors is reduced, but chip area occupied by the circuit increases

Engineering Contradiction:

Improvemagnetic couplingVSAvoidchip area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent embeds the first inductor coil within the second inductor coil, creating a nested configuration where the inner coil is positioned inside the outer coil. This nesting approach allows both inductors to occupy the same spatial footprint, significantly reducing the chip area required while maintaining magnetic isolation through the figure-of-eight configuration that cancels magnetic coupling effects.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent converts the potentially harmful magnetic coupling effect into a beneficial cancellation mechanism by using the figure-of-eight configuration. The magnetic fields generated by the inner coil in opposite directions are designed to cancel each other out, transforming what would normally be a harmful coupling effect into a mechanism that actively reduces magnetic interference while enabling compact integration.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Area of stationary object

If inductors are embedded within each other to reduce chip area, then chip area is minimized, but the ability to operate inductors independently is lost

Engineering Contradiction:

Improvechip areaVSAvoidindependent operation capability

Core Design Contradiction:

Area of stationary objectVSAdaptability or versatility

Solution Approach 1:

The patent segments the inductor structure into distinct first and second inductor coils with separate terminals and independent current paths. The figure-of-eight configuration divides the inner coil into two symmetrical loops that can be independently controlled, allowing each inductor to be activated or deactivated separately while maintaining the compact nested structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent enables dynamic configuration where the inductors can operate in multiple modes: independently as separate inductors, or together as a composite inductor structure. The circuit design allows switching between different operational states, providing adaptability that maintains versatility despite the embedded configuration.

Inventive Principle:

Principle #15Dynamics

3Area of stationary object

If inductors are embedded within each other to reduce chip area, then chip area is minimized, but Q-factor performance deteriorates due to unwanted coupling effects

Engineering Contradiction:

Improvechip areaVSAvoidQ-factor performance

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent employs asymmetric winding directions for the two loops of the figure-of-eight configuration, with one loop wound clockwise and the other counter-clockwise. This asymmetry in winding direction creates opposing magnetic field polarities that enable cancellation of magnetic coupling effects, thereby maintaining high Q-factor performance in the embedded structure.

Inventive Principle:

Principle #4Asymmetry

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 minimizes chip area, allows for independent or concurrent operation of inductors, and maintains high Q-factor performance by canceling electromagnetic fields, thus optimizing the use of silicon area and reducing unwanted coupling effects.

Implementation Method 1

the magnetic effect of a current flowing through the inductor 201 cancels that of the outer inductors 203 and 204 such that no magnetic coupling of these coils occurs

Methodology Applied

Scientific EffectElectromagnetic field cancellation: Electromagnetic Induction

Data Source

PatentUS9543068B2Inductor structure and application thereof

Publication Date: 2017.01.10 QUALCOMM TECH INT

AI summary

The present disclosure relates to composite inductor structures for use in integrated circuits. There is provided a composite inductor structure comprising a first inductor coil and a second inductor coil. The second inductor coil comprises a multi-turn loop that surrounds the first inductor coil. The first inductor coil comprises two multi-turn loops which are connected in a figure-of-eight configuration about a central terminal so as to cause a current flowing in a first loop of the multi-turn loops to circulate around the first loop in a first rotational direction, and a current flowing in a second loop of the multi-turn loops to circulate around the second loop in a second rotational direction opposite the rotational direction of current flow in the first loop, said direction of current flow in the first and second loops being mirror images of each other.