VCO Supply Noise Cancellation via Programmable Gain Varactor

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Solution Overview

Problem

Voltage controlled oscillators (VCOs) in electronic devices suffer from supply noise interference, which degrades their performance and increases noise sensitivity, especially when combined with other circuits sharing a common power supply, and existing solutions like regulators add noise and increase current consumption.

Innovation Solution

A VCO core with integrated noise cancellation paths, utilizing programmable gain circuits and varactors to minimize the difference between cancellation noise and modified noise, thereby reducing output noise and improving noise cancellation efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If regulators are used to reduce supply noise, then power supply stability is improved, but current consumption increases and additional noise is introduced

Engineering Contradiction:

Improvepower supply stabilityVSAvoidcurrent consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent introduces an intermediary noise cancellation path that includes a programmable gain circuit and varactor tuned to match the noise characteristics. This intermediary path generates an inverted noise signal that cancels the supply noise at the VCO input, acting as a mediator between the noisy power supply and the sensitive VCO, thereby reducing the need for heavy-duty regulators.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The noise cancellation path performs preliminary anti-action by pre-generating an inverted noise signal that counteracts the supply noise before it reaches the VCO core. The programmable gain circuit and tuned varactor are configured to match the noise characteristics in advance, creating a preemptive cancellation effect that reduces both the need for aggressive filtering and high current consumption.

Inventive Principle:

Principle #9Preliminary anti-action

2Reliability

If regulators are used to reduce supply noise, then power supply stability is improved, but additional noise is introduced

Engineering Contradiction:

Improvepower supply stabilityVSAvoidregulator noise

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The noise cancellation path serves as an intermediary that directly addresses supply noise without requiring regulators. By injecting an inverted noise signal through the programmable gain circuit and tuned varactor, the system cancels supply noise at the VCO input level, completely avoiding the introduction of regulator noise while maintaining power supply stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful supply noise into a beneficial cancellation signal. By capturing the supply noise characteristics through the noise path and regenerating them in inverted phase through the cancellation path, the system transforms the harmful noise into a useful counter-signal that actively eliminates the original noise source.

Inventive Principle:

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

3Object-affected harmful factors

If noise cancellation paths are added, then noise sensitivity is reduced, but device complexity increases

Engineering Contradiction:

Improvenoise sensitivityVSAvoidcircuit complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent segments the VCO circuit into distinct functional paths: a noise path that captures supply noise characteristics, a cancellation path that generates inverted noise signals, and the core VCO circuit. This segmentation allows each path to be optimized independently with specific components (programmable gain circuit for the cancellation path, tuned varactor for noise matching), reducing overall complexity through modular design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The noise cancellation mechanism serves multiple functions simultaneously: it reduces noise sensitivity, maintains frequency stability, and works across different supply noise conditions through programmable gain adjustment. The same cancellation path structure can be applied to various VCO designs and noise environments, providing a universal solution that reduces complexity through reuse of the proven architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 effectively reduces the sensitivity of VCOs to supply noise, minimizing phase and frequency noise, and can be implemented with or without regulators, enhancing the performance of VCOs in electronic devices.

Implementation Method 1

The cancellation path includes a programmable gain circuit coupled with a first terminal of a varactor

Methodology Applied

Scientific EffectVaractor effect:

Implementation Method 2

The supply noise passes through the programmable gain circuit to produce a cancellation noise

Methodology Applied

Scientific EffectSignal amplification:

Data Source

PatentUS8981862B2Cancelling supply noise in a voltage controlled oscillator circuit

Publication Date: 2015.03.17 QUALCOMM INC

AI summary

A voltage controlled oscillator (VCO) core for cancelling a supply noise is described. The VCO core includes an input node that receives the supply noise. The VCO core also includes a noise path coupled to the input node. The VCO core additionally includes a cancellation path coupled to the input node and the noise path. The cancellation path includes a programmable gain circuit coupled with a first terminal of a varactor. The supply noise passes through the programmable gain circuit to produce a cancellation noise.