EMI Suppression Circuit Frequency Jitter Switch Mode Power Supply
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Solution Overview
Problem
Switch mode power supplies in electronic apparatuses generate significant electromagnetic interference (EMI) due to high operating frequencies, which existing filtering methods like common mode inductors and capacitors struggle to effectively suppress, especially in terms of size, cost, and reliability.
Innovation Solution
An electromagnetic interference suppression circuit employing a signal generating sub-circuit and a frequency generating sub-circuit that outputs frequency-jittered drive signals to the switch mode power supply, broadening the frequency band and reducing peak energy of subharmonics to effectively suppress EMI, while maintaining reduced size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If filtering components such as common mode inductors and capacitors are used to suppress EMI, then EMI suppression effect is improved, but device size and cost increase
Solution Approach 1:
The patent changes the operating frequency parameter of the switch mode power supply by introducing frequency jitter through a frequency generating sub-circuit. This modifies the fixed high-frequency operation to a dynamically varying frequency, which suppresses EMI by dispersing electromagnetic energy across a broader frequency spectrum rather than concentrating it at a single frequency, thereby reducing the need for large filtering components
Solution Approach 2:
The patent replaces the traditional mechanical/filtering-based EMI suppression approach (using physical inductors and capacitors) with an electronic control approach. By using signal generating and frequency generating sub-circuits to modulate the operating frequency, the system achieves EMI suppression through electronic parameter modulation rather than physical filtering components
2Object-affected harmful factors
If filtering components such as common mode inductors and capacitors are used to suppress EMI, then EMI suppression effect is improved, but manufacturing cost increases
Solution Approach 1:
The patent achieves EMI suppression by changing the frequency parameter dynamically through control circuits rather than using expensive high-performance filtering components. The frequency generating sub-circuit modulates the operating frequency to achieve broadband EMI suppression, which is more cost-effective than using premium inductors and capacitors
Solution Approach 2:
The patent uses relatively simple and inexpensive signal generating and frequency generating sub-circuits instead of costly filtering components. The electronic control approach employs basic circuit elements that are cheaper and easier to manufacture than high-performance electromagnetic filtering components
3Object-affected harmful factors
If traditional filtering methods are used to suppress EMI, then EMI reduction is achieved, but reliability is compromised
Solution Approach 1:
The patent improves reliability by using frequency modulation rather than passive filtering components that can degrade over time. The active control approach continuously adapts the operating frequency, avoiding the reliability issues associated with aging inductors and capacitors while maintaining effective EMI suppression
Data Source
AI summary
An electromagnetic interference suppression circuit, a driving method thereof, and an electronic apparatus are provided. In the electromagnetic interference suppression circuit, a signal generating sub-circuit may generate a plurality of parallel target sequence signals, each with a period greater than a period threshold and a quantity of target sequence signals greater than a quantity threshold; and a frequency generating sub-circuit may output a frequency-jittered drive signal, for driving a switch mode power supply to operate, to the switch mode power supply under the control of the plurality of parallel target sequence signals.