Memory Card Control Chip Spread Spectrum EMI Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional methods for reducing electromagnetic interference (EMI) in memory card access devices, such as using external resistors, become costly and reduce clock signal driving ability as EMI certification criteria become more stringent, leading to compatibility issues.
Innovation Solution
A memory card control chip employing spread spectrum technology, specifically a phase lock loop with a spread spectrum function, generates and transmits spread spectrum clock signals to memory cards, dynamically adjusting frequency to reduce EMI while maintaining clock signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If external resistors with higher resistance are used to reduce EMI, then EMI certification is passed, but clock signal driving ability is reduced and cost increases
Solution Approach 1:
The patent changes the parameter of the clock signal from a traditional single-frequency signal to a spread spectrum signal with dynamically varying frequency. The frequency is modulated according to a pseudo-random code, spreading the energy spectrum and reducing peak EMI intensity while maintaining the signal's driving capability through controlled frequency variation rather than resistance-based attenuation
Solution Approach 2:
The patent replaces the mechanical/electrical approach of using external resistors to reduce EMI with an electronic signal processing approach. Instead of passively attenuating the signal through resistance, the system actively modulates the clock signal frequency using a pseudo-random code generator and modulator, achieving EMI reduction without compromising signal strength or requiring additional external components
2Object-affected harmful factors
If external resistors with higher resistance are used to reduce EMI, then EMI certification is passed, but manufacturing cost increases
Solution Approach 1:
The patent merges the EMI reduction function with the existing clock signal generation circuitry by integrating a pseudo-random code generator and modulator within the memory card control chip. This eliminates the need for separate external resistors and combines multiple functions (clock generation, modulation, and EMI reduction) into a single integrated solution, reducing component count and manufacturing cost
Solution Approach 2:
The patent replaces expensive passive external resistors with integrated electronic circuit elements that can be manufactured at lower cost using standard semiconductor fabrication processes. The spread spectrum implementation uses software-controlled frequency modulation rather than hardware-based attenuation, reducing bill of materials costs while achieving the same EMI certification goal
3Object-affected harmful factors
If external resistors with higher resistance are used to reduce EMI, then EMI certification is passed, but compatibility problems occur
Solution Approach 1:
The patent implements a dynamic frequency modulation scheme where the clock signal frequency varies over time according to a pseudo-random code. This dynamic behavior allows the signal to adapt to different loading conditions and memory card types, maintaining compatibility while reducing peak EMI intensity through frequency spreading rather than amplitude attenuation
Solution Approach 2:
The spread spectrum clock signal generation circuit is designed to be universally compatible with different memory card types and interfaces. By modulating the frequency rather than attenuating the signal, the solution maintains signal integrity across various impedance conditions and card specifications, making it applicable to SD, MMC, and other memory card standards without requiring type-specific adjustments
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 spread spectrum technology effectively reduces EMI without compromising clock signal quality, meeting stringent certification criteria while minimizing costs and ensuring compatibility with various memory card types.
Implementation Method 1
The second clock signal is a spread spectrum clock signal
Implementation Method 2
A memory card control chip employing spread spectrum technology, specifically a phase lock loop with a spread spectrum function, generates and transmits spread spectrum clock signals to memory cards
Data Source
AI summary
The invention discloses a memory card control chip. The memory card control chip comprises a clock generator, a first memory card interface, and a control circuit. The clock generator generates a first clock signal and a second clock signal. The second clock signal is a spread spectrum clock signal. The first memory card interface is coupled to the clock generator and comprises a first clock signal pin and a plurality of first data signal pins. The first memory card interface is connected to a first memory card to be a data transmission interface of the first memory card. The first clock signal pin transmits the second clock signal. The control circuit is coupled to the first memory card interface and receives the first clock signal for performing the data accessing of the first memory card.