EMI Suppression via PLL Frequency Segmentation
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Solution Overview
Problem
Current methods for eliminating electromagnetic interference (EMI) from electronic products, particularly inductors in ICs, are inadequate as they either fail to suppress radiated interference or are ineffective for high-power circuits.
Innovation Solution
A device comprising a timing control chip and a phase-locked loop module with phase detection, charge pump, voltage-controlled oscillator, and frequency divider units generates multiple switching frequencies to reduce radiated interference by decentralizing power circuit frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If RC buffer circuit is used, then low-power circuit EMI is reduced, but it is ineffective for high-power circuits
Solution Approach 1:
The patent applies frequency segmentation to high-power circuits by generating multiple harmonic frequencies from the switching signal. This disperses the EMI energy that would otherwise be concentrated at the fundamental frequency, making the solution effective for high-power applications where RC buffers fail.
Solution Approach 2:
The patent changes the frequency parameter by generating harmonic multiples, which fundamentally alters how EMI is distributed in high-power circuits. This frequency transformation approach works effectively for high-power circuits unlike RC buffers, because it addresses the root cause of radiated EMI rather than merely filtering it.
2Device complexity
If single switching frequency is used to drive power chip, then circuit operation is simple, but severe EMI radiation occurs
Solution Approach 1:
The patent segments the concentrated switching frequency into multiple harmonic frequency components. The frequency multiplication module generates 2nd, 3rd, 4th and higher-order harmonics, which disperses the EMI energy across multiple frequency bands, thereby reducing severe radiation at the fundamental frequency while maintaining relatively simple circuit operation.
Solution Approach 2:
The patent utilizes periodic harmonic generation where each harmonic frequency represents a periodic component of the switching signal. The frequency multiplication module generates periodic harmonic waves at integer multiples of the fundamental frequency, creating a structured multi-frequency output that reduces EMI radiation.
Data Source
AI summary
This application relates to a device and a method for eliminating electromagnetic interference (EMI). The device for eliminating EMI includes: a timing control chip; and a phase-locked loop module, electrically connected to the timing control chip and including: a phase detection unit, configured to detect a frequency generated by a clock cycle to generate a frequency difference; a charge pump unit, configured to generate a regulation voltage; a voltage-controlled oscillator unit, configured to control an oscillation frequency when the regulation voltage is input; a plurality of frequency divider units, configured to generate a new output clock frequency by using an input clock frequency; and a selector unit, configured to select the appropriate frequency divider units, where the selector unit has another end electrically connected to needed power circuits.