Switching Regulator EMI Reduction via Noise-Modulated Sawtooth

Solution Overview

Problem

Existing switching regulators in mobile communication systems face challenges in reducing electromagnetic interference (EMI) without increasing device size and cost, as current methods like large filters and shielding are inefficient.

Innovation Solution

A switching regulator that converts noise voltage into a noise current and outputs a sawtooth voltage signal with varying frequency, using a voltage-to-current converter and sawtooth generator, integrated into a single semiconductor chip, to effectively mitigate EMI.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a large filter and shielding are used to reduce EMI, then EMI reduction is improved, but device size and cost increase

Engineering Contradiction:

ImproveEMI reductionVSAvoiddevice size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of stationary object

Solution Approach 1:

The patent changes the frequency parameter of the switching regulator by adding noise to the sawtooth waveform, transforming the EMI characteristics from a fixed high-amplitude signal to a variable frequency signal with lower peak amplitude, thereby reducing EMI without requiring larger filters or shielding

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful noise signal into a beneficial element by using it to modulate the sawtooth waveform frequency, thereby transforming the noise from a source of EMI into a mechanism for EMI reduction through frequency spreading

Inventive Principle:

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

2Object-affected harmful factors

If a large filter and shielding are used to reduce EMI, then EMI reduction is improved, but device cost increases

Engineering Contradiction:

ImproveEMI reductionVSAvoiddevice cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent changes the frequency parameter of the switching regulator by adding noise to the sawtooth waveform, transforming the EMI characteristics from a fixed high-amplitude signal to a variable frequency signal with lower peak amplitude, thereby reducing EMI without requiring larger filters or shielding

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful noise signal into a beneficial element by using it to modulate the sawtooth waveform frequency, thereby transforming the noise from a source of EMI into a mechanism for EMI reduction through frequency spreading

Inventive Principle:

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

3Volume of stationary object

If spread spectrum technique is used to reduce EMI filter size, then filter size is reduced, but the technique has its own disadvantages

Engineering Contradiction:

ImproveEMI filter sizeVSAvoidtechnique complexity

Core Design Contradiction:

Volume of stationary objectVSDevice complexity

Solution Approach 1:

The patent merges the EMI reduction function with the existing switching regulator control circuitry by modifying the sawtooth waveform generation, integrating frequency spreading directly into the pulse width modulation mechanism rather than using a separate spread spectrum module

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The switching regulator's own noise signal is used to modulate its control waveform, allowing the system to perform EMI reduction using its internally generated signals rather than requiring external control mechanisms

Inventive Principle:

Principle #25Self-service

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 reduces EMI by generating a sawtooth voltage signal with a frequency that varies based on noise current levels, thereby minimizing electromagnetic interference while maintaining a compact and cost-effective design.

Implementation Method 1

a voltage-to-current converter configured to convert a noise voltage signal into a noise current and output the noise current

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

an operational amplifier configured to amplify and output an input voltage formed by adding the noise voltage, to or subtracting the noise voltage from, a DC voltage output from a power source

Methodology Applied

Scientific EffectElectromagnetic amplification: Electromagnetic Induction

Implementation Method 3

The sawtooth generator comprises a capacitor for converting the noise current into the sawtooth voltage signal and outputting the sawtooth voltage signal

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS9148052B2Switching regulator with reduced EMI

Publication Date: 2015.09.29 SAMSUNG ELECTRONICS CO LTD

AI summary

The switching regulator includes a voltage-to-current converter to convert a noise voltage into a noise current and output the noise current; and a sawtooth generator to output a sawtooth voltage signal having a frequency that varies in response to the noise current output from the voltage-to-current converter.