Clock Frequency Modulation for EMI Reduction Across Isolation Barriers
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Solution Overview
Problem
High frequency clock signals in electronic devices often cause electromagnetic interference (EMI) due to energy concentration at specific frequencies, which existing techniques struggle to effectively mitigate.
Innovation Solution
A frequency modulator system comprising a core oscillator and a clock divider that modulates the clock signal's frequency, spreading spectral components to reduce EMI, and includes a circuit to combine the digital clock signal with a data bitstream for transmission across an isolation barrier, ensuring synchronization and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high frequency clock signals are used for timing functions, then timing precision and operation speed are improved, but electromagnetic interference increases due to energy concentration at specific frequencies
Solution Approach 1:
The patent applies dynamics by making the clock signal frequency variable rather than fixed. The frequency modulator continuously varies the clock frequency around a central value, transforming the static high-frequency signal into a dynamic signal that spreads energy across multiple frequencies, thereby reducing EMI while maintaining operational speed requirements
Solution Approach 2:
The patent changes the frequency parameter of the clock signal by introducing frequency modulation. The modulator alters the frequency parameter dynamically, spreading the concentrated spectral energy into a broader frequency spectrum, which reduces the harmful EMI effect while preserving the timing functionality
2Object-generated harmful factors
If frequency modulation is applied to spread spectral components, then electromagnetic interference is reduced, but signal synchronization becomes more challenging
Solution Approach 1:
The patent implements feedback mechanisms through phase-locked loops (PLL) and synchronization circuits that continuously monitor the modulated clock signal and adjust accordingly. This feedback ensures that despite frequency variations for EMI reduction, the signal maintains proper synchronization and timing relationships
Solution Approach 2:
The patent uses periodic frequency modulation patterns where the clock frequency varies in a controlled, repeating manner. This periodic action allows receiving circuits to anticipate and synchronize with the modulation pattern, maintaining reliability while achieving EMI reduction through spectral spreading
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 electromagnetic interference by deterministically spreading clock spectral components, limiting cycle-to-cycle jitter, and synchronizing signals across an isolation barrier, thereby improving emissions and communication efficiency.
Implementation Method 1
The illustrative frequency modulator comprises a core oscillator 102, and a clock divider 104 coupled to the core oscillator that modulates frequency of the core oscillator and deterministically spreads clock spectral components of a digital clock signal whereby electromagnetic interference (EMI) is reduced
Data Source
AI summary
In an electronic system, a frequency modulator manages clock signals for electromagnetic interference (EMI) reduction. The illustrative frequency modulator comprises a core oscillator, and a clock divider coupled to the core oscillator that modulates frequency of the core oscillator and deterministically spreads clock spectral components of a digital clock signal whereby electromagnetic interference (EMI) is reduced. The frequency modulator further comprises a circuit coupled to the clock divider that receives the digital clock signal, combines the digital clock signal with a data bitstream for transmission across an isolation barrier, and resynchronizes to the digital clock signal.