Current Pulse Matching for Switched Mode Power Converter Noise

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Solution Overview

Problem

High switching frequency in switch mode power conversion applications leads to output voltage disturbances and noise due to parasitic capacitance and inductance in traditional silicon-based MOSFETs, which are not effectively addressed by existing solutions.

Innovation Solution

A control circuit with a current pulse matching module is integrated into the power driver IC, utilizing a rate-of-voltage change detection circuit driven by the power converter switch node to source/sink a matching current pulse that cancels out the power stage current pulse, thereby eliminating output voltage disturbances and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high switching frequency is used in switch mode power conversion, then power conversion efficiency and response speed are improved, but output voltage disturbances and noise increase due to parasitic capacitance and inductance

Engineering Contradiction:

Improvepower conversion efficiencyVSAvoidoutput voltage disturbances and noise

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by detecting the voltage change rate (dV/dt) across the switch and generating a compensating current pulse in advance to counteract the harmful effects of parasitic capacitance and inductance. The compensation circuit proactively creates a current pulse that opposes the voltage disturbance before it fully manifests at the output, thereby maintaining stable output voltage even at high switching frequencies

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent introduces an intermediary compensation circuit between the power switch and the output load. This intermediary circuit includes a compensation capacitor and controlled current source that mediates the harmful interaction between the switch's parasitic elements and the output voltage. The intermediary detects dV/dt and generates a compensating current that isolates the output from voltage disturbances caused by parasitic capacitance and inductance

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If traditional silicon-based MOSFETs are used, then device reliability is maintained, but switching speed is limited to 2-3 MHz due to parasitic capacitance and inductance

Engineering Contradiction:

Improvedevice reliabilityVSAvoidswitching frequency

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent applies parameter changes by modifying the electrical characteristics of the switching circuit through active compensation. By dynamically adjusting the compensating current based on detected dV/dt rates, the system effectively changes the electrical parameters (voltage, current) to counteract the limiting effects of parasitic capacitance and inductance, enabling reliable operation at switching frequencies beyond the traditional 2-3 MHz limit

Inventive Principle:

Principle #35Parameter changes

3Productivity

If switching speed is increased beyond 2-3 MHz, then power conversion efficiency improves, but parasitic capacitance and inductance cause voltage disturbances that existing solutions cannot effectively address

Engineering Contradiction:

Improvepower conversion efficiencyVSAvoidvoltage disturbances from parasitic elements

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent implements feedback by continuously monitoring the voltage change rate (dV/dt) across the power switch and using this information to control the compensating current source. The feedback loop measures the actual voltage stress on the switch and dynamically adjusts the compensation magnitude and timing, enabling the system to effectively counteract parasitic effects at high switching frequencies where traditional fixed compensation methods fail

Inventive Principle:

Principle #23Feedback

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 output voltage disturbances and noise during high switching rate power conversion, enabling stable operation even at high frequencies without the need for external discrete components, thus enhancing power system performance.

Implementation Method 1

utilizing a rate-of-voltage change detection circuit driven by the power converter switch node

Methodology Applied

Scientific EffectRate of voltage change detection:

Implementation Method 2

source/sink a matching current pulse that cancels out the power stage current pulse, thereby eliminating output voltage disturbances and noise

Methodology Applied

Scientific EffectCurrent pulse cancellation:

Data Source

PatentUS11323019B2System and method for current pulse matching technique in a switched mode power converter

Publication Date: 2022.05.03 UNIVERSITY OF LIMERICK

AI summary

A switched mode power supply converter comprises a circuit pulse matching circuit configured to negate output voltage disturbance or noise during switching operation of a power conversion. The current pulse matching circuit input is driven by, or from, a power converter switch node of the switched mode power supply converter. The current pulse matching circuit comprises a rate-of-voltage change detection circuit driven by the power converter switch node.