Adaptive Spread-Spectrum Modulation for Variable Clock EMI Control
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Solution Overview
Problem
Existing serializer and deserializer systems face challenges in reducing electromagnetic interference (EMI) due to fixed clock frequencies, leading to high energy concentration at specific frequencies, which can cause interference and require expensive shielding solutions, and modulation frequency variations can result in audio interference or be beyond the recovery capabilities of downstream devices.
Innovation Solution
A system that generates a spread-spectrum signal by controlling the modulation frequency based on the input signal frequency, using a detector, controller, modulation signal generator, and spread-spectrum signal generator to maintain the modulation frequency within a defined range, thereby reducing EMI and preventing adverse operational effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed frequency clock signal is used to drive the serializer, then the data transmission rate is stable and reliable, but the energy concentrates at a single frequency causing high EMI that requires expensive shielded cables and housings
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed frequency clock signal to a dynamically varying spread-spectrum clock signal. The clock frequency is modulated to vary within a defined range, which spreads the energy spectrum and reduces EMI while maintaining data transmission reliability through controlled frequency variation.
Solution Approach 2:
The patent changes the frequency parameter of the clock signal from a fixed value to a varying value within a defined range. By modulating the clock frequency and controlling its spectral distribution, the system achieves both reduced EMI and maintained transmission stability through parameter optimization.
2Adaptability or versatility
If the modulation frequency varies with the clock signal frequency over a wide range, then the system is adaptable to different data rates, but the modulation frequency may fall into audio bands causing interference or exceed downstream device recovery capabilities
Solution Approach 1:
The patent implements feedback by continuously monitoring the clock signal frequency and adjusting the modulation frequency accordingly. The system measures the actual clock frequency and controls the spread-spectrum modulation to maintain the modulation frequency within a safe range that avoids audio bands and remains within downstream device recovery capabilities, regardless of data rate variations.
Solution Approach 2:
The system dynamically adjusts the modulation frequency based on the actual clock signal frequency and data rate requirements. By making the modulation frequency adaptive rather than fixed, the system maintains versatility across different data rates while preventing harmful frequency excursions through real-time control.
3Object-generated harmful factors
If specialized shielded wired mediums are used to reduce EMI, then electromagnetic interference is substantially reduced, but the system becomes expensive and consumes large physical footprint
Solution Approach 1:
The patent converts the potentially harmful concentrated energy spectrum into a beneficial spread-spectrum signal. By intentionally spreading the clock signal energy across a frequency range, the system transforms what would be a harmful EMI issue into a solution that inherently reduces interference, eliminating the need for expensive shielded cables and housings.
Data Source
AI summary
An apparatus for generating a spread-spectrum signal based on an input signal whose frequency may vary substantially. The apparatus is particularly suited for controlling the frequency of the modulation in response to wide variations of the frequency of the input signal. This prevents the modulation frequency from deviating into an undesired frequency range which could cause adverse operational effects. The apparatus includes a detector adapted to generate a first signal related to the frequency of the input signal, a controller adapted to generate a second signal for controlling a frequency of a modulation signal based on the first signal, a modulation signal generator adapted to generate the modulation signal based on the second signal, and a spread-spectrum signal generator adapted to generate the spread-spectrum signal based on the modulation signal.