Spread Spectrum Clocking for Switching Converters Across EMI Bands
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Solution Overview
Problem
Conventional spread spectrum modulation methods are limited in their performance and applicability, only effectively functioning within specific frequency bands (150 kHz to 30 MHz and 30 MHz to 1 GHz), failing to provide adequate performance across both low and high frequency bands.
Innovation Solution
A switching power converter circuit and clock generator circuit that utilize a combination of periodic and random waveforms to generate a spread spectrum control signal, incorporating a variable frequency oscillator, pulse width modulation circuit, and computation unit to create a spread spectrum clock signal with a fundamental frequency and switching frequency variation, thereby enhancing spread spectrum performance and expanding its frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic analog spread spectrum modulation method is used, then spread spectrum performance is improved in frequency band of 150 kHz to 30 MHz, but performance deteriorates in frequency band above 30 MHz
Solution Approach 1:
The patent combines periodic analog spread spectrum modulation method and frequency hopping spread spectrum modulation method into a unified system. The controller selectively applies periodic modulation for frequency band 150 kHz to 30 MHz and frequency hopping for frequency band 30 MHz to 1 GHz, achieving comprehensive performance across the entire frequency range.
2Reliability
If frequency hopping spread spectrum modulation method is used, then spread spectrum performance is improved in frequency band of 30 MHz to 1 GHz, but performance deteriorates in frequency band below 30 MHz
Solution Approach 1:
The patent integrates frequency hopping spread spectrum modulation method with periodic analog spread spectrum modulation method. The controller determines the operating frequency band and selects the appropriate modulation method: frequency hopping for 30 MHz to 1 GHz and periodic modulation for 150 kHz to 30 MHz, ensuring optimal performance across the full spectrum.
3Device complexity
If single spread spectrum modulation method is used, then device complexity is reduced, but adaptability to different frequency bands deteriorates
Solution Approach 1:
The patent implements a dynamic modulation system where the controller adjusts the spread spectrum modulation method based on the operating frequency band. The system transitions between periodic analog modulation and frequency hopping modulation according to real-time frequency conditions, optimizing performance without requiring separate fixed systems for each band.
Data Source
AI summary
A spread spectrum switching power converter circuit includes: a power stage circuit which includes an inductor and a power switch and is configured to switch the power switch according to a switching signal having spread spectrum for power conversion; a variable frequency oscillator, which generates a spread spectrum clock signal according to a spread spectrum control signal; a spread spectrum control circuit, which generates the spread spectrum control signal according to a first clock signal and a second clock signal; and a pulse width modulation circuit, configured to generate the switching signal according to a feedback signal based on the spread spectrum clock signal. The spread spectrum control circuit generates the spread spectrum control signal by sampling and combining a periodic waveform and a random waveform. The random waveform is generated according to the first clock signal and the periodic waveform is generated according to the second clock signal.