Voltage Controlled Variable Capacitor Linearity via Anti-Parallel Networks

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Solution Overview

Problem

Voltage Variable Capacitors (VVCs) suffer from AC signal distortion due to intermodulation products and harmonics, limiting their application in linear electronic circuits.

Innovation Solution

The use of anti-parallel and anti-series VVC networks, where VVCs are biased in opposite polarities, is employed to create a compensation network that reduces AC capacitive variations, thereby improving linearity by combining these networks in various configurations such as parallel and series arrangements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If VVCs are used to actively adjust electronic circuits, then capacitance control range is improved, but AC signal distortion increases due to intermodulation products and harmonics

Engineering Contradiction:

Improvecapacitance control rangeVSAvoidAC signal distortion

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent combines multiple VVCs in specific circuit configurations (anti-parallel and anti-series networks) to merge their individual capacitance control capabilities while canceling out their non-linear distortion effects. This allows the system to maintain wide capacitance adjustment range while reducing AC signal distortion through the collective behavior of the combined VVC network.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent converts the inherent non-linear characteristics of individual VVCs, which normally produce distortion, into a beneficial effect by arranging them in anti-parallel and anti-series configurations. The non-linearities of individual VVCs generate opposing distortion components that cancel each other out, transforming the harmful distortion into a linearity-improving mechanism.

Inventive Principle:

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

2Reliability

If anti-parallel and anti-series VVC networks are used to reduce distortion, then linearity is improved, but device complexity increases

Engineering Contradiction:

ImprovelinearityVSAvoidcircuit configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the VVC system into distinct functional blocks (anti-parallel networks and anti-series networks), each designed to address specific aspects of non-linearity. This segmentation allows for modular design, where each segment can be independently optimized and analyzed, making the overall complex system more manageable and implementable.

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

This approach significantly reduces non-linearity in VVCs, allowing for more constant net capacitance with respect to AC voltages while maintaining a wide range of capacitance control, thereby enhancing the linearity and reducing distortions, as demonstrated by improved third harmonic performance up to 35 dB.

Implementation Method 1

Voltage Variable Capacitors (VVCs) are used effectively in many applications to actively adjust electronic circuits

Methodology Applied

Scientific EffectVoltage-dependent capacitance: Capacitance

Implementation Method 2

at least one anti-parallel pair VVC network comprised of two parallel VVCs with one biased in the opposite polarity of the other and at least one anti-series VVC network comprised of two VVCs configured in series, one biased in the opposite polarity of the other such that the resulting AC capacitive variations produce a desired AC capacitance variation

Methodology Applied

Scientific EffectCapacitance cancellation: Capacitance

Data Source

PatentUS7777369B2Apparatus, system and methods for enabling linearity improvement in voltage controlled variable capacitors

Publication Date: 2010.08.17 NXP USA INC

AI summary

An embodiment of the present invention provides an apparatus, comprising at least one anti-parallel pair VVC network comprised of two parallel VVCs with one biased in the opposite polarity of the other and at least one anti-series VVC network comprised of two VVCs configured in series, one biased in the opposite polarity of the other such that the resulting AC capacitive variations produce a desired capacitance variation.