Switchable Inductor Network for Wideband RF Circuits

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Solution Overview

Problem

Conventional switchable inductors in RF circuits face a tradeoff between area occupancy and quality factor (Q), where reducing area degrades Q, and existing methods for wideband frequency coverage increase power consumption and phase noise in voltage-controlled oscillators (VCOs).

Innovation Solution

A switchable inductor network comprising a first coil and a second coil with a switch that couples inductive segments to adjust inductance, allowing for selective inductance changes without significant degradation of the quality factor, using a configuration where the additional inductance is in series and greater than mutual inductance between coils.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple VCOs are used to cover wide frequency range, then frequency coverage is improved, but power consumption and die area increase

Engineering Contradiction:

Improvefrequency coverageVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

A single VCO is designed to perform multiple frequency bands by integrating a switchable inductor network that can be configured for different inductance values, allowing one oscillator to replace multiple frequency-specific VCOs

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The inductor network incorporates switches that dynamically reconfigure the inductance value based on the desired frequency band, enabling the VCO to adapt its resonant frequency without requiring multiple fixed-frequency oscillators

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If conventional approaches are used to widen VCO tuning range, then frequency coverage is improved, but phase noise increases

Engineering Contradiction:

Improvetuning rangeVSAvoidphase noise

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The inductor is divided into multiple segments that can be selectively connected or disconnected via switches, allowing the tuning range to be extended by combining different segments while maintaining optimal Q-factor for each segment configuration

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different segments of the inductor are designed with specific inductance values optimized for particular frequency ranges, allowing each segment to contribute to the overall performance without degrading phase noise in any specific band

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If dual-mode resonance tanks with switched inductor are used, then frequency coverage is improved, but inductor Q degrades

Engineering Contradiction:

Improvefrequency bandsVSAvoidinductor Q

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The switchable inductor network dynamically reconfigures the inductance by selectively connecting different segments based on the operating frequency band, ensuring that the inductor Q remains high in both low and high frequency modes

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The inductance parameter is changed by switching between different segment configurations, allowing the system to optimize the Q-factor for each frequency band by selecting the appropriate inductance value

Inventive Principle:

Principle #35Parameter changes

4Area of stationary object

If inductor area is reduced, then die area is improved, but inductor Q degrades

Engineering Contradiction:

Improvedie areaVSAvoidinductor Q

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The inductor is segmented into multiple smaller units that can be arranged in series or parallel configurations, allowing the total inductance to be achieved with smaller individual components that occupy less die area while maintaining high Q-factor through optimal segment design

Inventive Principle:

Principle #1Segmentation

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 solution enables efficient area usage and maintains high Q values across different frequency bands, reducing power consumption and phase noise in VCOs, thus enhancing the performance of wideband RF circuits.

Implementation Method 1

A switchable inductor network for wideband circuits provides selectable inductance. The switchable inductor network includes a first coil and a second coil that includes a first inductive segment and a second inductive segment.

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10447204B2Switchable inductor network for wideband circuits

Publication Date: 2019.10.15 QUALCOMM INC

AI summary

The present disclosure describes aspects of a switchable inductor network for wideband circuits. In some aspects, the switchable inductor network provides selectable inductance. The switchable inductor network includes a first coil and a second coil that includes a first inductive segment and a second inductive segment. Connection points of the second coil connect the second coil across a portion of the first coil. The switchable inductor network also includes a switch connected between the first inductive segment and the second inductive segment of the second coil. The switch is configured to change the selectable inductance of the switchable inductor network by selectively coupling the first inductive segment to the second inductive segment of the second coil in response to a control signal.