Variable Inductance VCO Circuitry for Wider Frequency Tuning

Solution Overview

Problem

Current Integrated Circuit (IC) based Voltage Controlled Oscillators (VCOs) face challenges in achieving a wide range of frequency adjustment due to the limitations of variable capacitance, often requiring complex and space-intensive circuitry, and there is a need for further advancements in frequency control technologies.

Innovation Solution

A unique variable inductance arrangement is implemented using two substrates with inductors that are electromagnetically coupled, allowing for the selection of different mutual inductance relationships through switch-controlled circuits, enabling adjustable inductance and frequency ranges for VCOs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If variable capacitance devices are used to provide frequency adjustment in VCOs, then frequency control capability is improved, but the circuit complexity and IC area increase

Engineering Contradiction:

Improvefrequency adjustment rangeVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the traditional electrical field-based variable capacitance mechanism with a magnetic field-based variable inductance mechanism. By using magnetically coupled inductors where the second inductor is controlled by a digital controller to vary its inductance, the system achieves frequency control through magnetic coupling rather than electrical capacitance variation, thereby simplifying the overall circuit architecture while maintaining wide frequency adjustment capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental control parameter from capacitance (C) to inductance (L). Instead of varying capacitance values to control VCO frequency, the invention varies the inductance of the resonant tank circuit by controlling the second inductor's inductance through digital control signals. This parameter substitution enables wide frequency tuning without requiring complex variable capacitance circuitry

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If variable capacitance devices are used to provide frequency adjustment in VCOs, then frequency control capability is improved, but the IC area increases

Engineering Contradiction:

Improvefrequency adjustment rangeVSAvoidIC area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent replaces the traditional electrical field-based variable capacitance mechanism with a magnetic field-based variable inductance mechanism. By using magnetically coupled inductors where the second inductor is controlled by a digital controller to vary its inductance, the system achieves frequency control through magnetic coupling rather than electrical capacitance variation, thereby simplifying the overall circuit architecture while maintaining wide frequency adjustment capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The second inductor serves multiple functions: it acts as part of the resonant tank circuit for frequency generation, functions as a variable inductance element controlled by digital signals, and provides magnetic coupling to achieve inductance variation. This multi-functionality reduces the need for separate variable capacitance devices and associated control circuitry, thereby reducing overall IC area

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If MOS varactors with PLL control are used to expand variable capacitance range, then frequency adjustment range is improved, but device complexity and IC area increase

Engineering Contradiction:

Improvevariable capacitance rangeVSAvoidcircuit enhancements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the traditional electrical field-based variable capacitance mechanism with a magnetic field-based variable inductance mechanism. By using magnetically coupled inductors where the second inductor is controlled by a digital controller to vary its inductance, the system achieves frequency control through magnetic coupling rather than electrical capacitance variation, thereby simplifying the overall circuit architecture while maintaining wide frequency adjustment capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Instead of varying capacitance to control frequency (the conventional approach), the patent inverts the approach by varying inductance while keeping capacitance relatively fixed. The resonant frequency is controlled by changing the inductance value of the second inductor through digital control, which inversely affects the frequency in opposition to the conventional capacitance-variation method

Inventive Principle:

Principle #13The other way round (Inversion)

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 allows for a wider range of frequency adjustment in VCOs while potentially simplifying the circuit design by reducing the need for variable capacitance, offering a more efficient and compact solution for frequency control.

Implementation Method 1

electromagnetically coupling the first and second inductors to provide a mutual inductance

Methodology Applied

Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Data Source

PatentUS8115557B2Variable inductance circuitry for frequency control of a voltage countrolled oscillator

Publication Date: 2012.02.14 NXP BV

AI summary

An electronic device is made from a first substrate with device circuitry including an inductor and a second substrate with inductance adjustment circuitry including a number of other inductors. The substrates are assembled together to be opposite one another. The other inductors are arranged to provide a selection of different mutual inductance relationships relative to the inductor. These relationships are selectable during operation of the device to provide a variable inductance in the device circuitry.