Analog Differentiator Spread Spectrum Clocking With Lower Circuit Complexity
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Solution Overview
Problem
Existing spread spectrum clock generators either increase complexity and power consumption to achieve high performance or rely on complex digital circuitry, which is not suitable for simple analog implementations.
Innovation Solution
A spread spectrum clock generator utilizing analog differentiating circuitry, including active and passive differentiators, to modulate the clock frequency, allowing for flexible waveform generation with reduced power consumption and circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If complex digital circuitry is used to achieve high performance spread spectrum modulation, then EMI reduction performance is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces complex digital circuitry with an analog differentiator circuit to generate the modulation waveform. The differentiator circuit uses simple analog components (resistors, capacitors, operational amplifier) to produce the required frequency modulation signal, eliminating the need for complex digital signal processing hardware while achieving the same EMI reduction effect
Solution Approach 2:
The patent changes the approach from digital parameter processing to analog parameter manipulation. By using an analog differentiator that directly processes voltage signals to generate the modulation waveform, the system achieves spread spectrum modulation through continuous analog parameter changes rather than discrete digital operations, reducing circuit complexity
2Object-affected harmful factors
If complex digital circuitry is used to achieve high performance spread spectrum modulation, then EMI reduction performance is improved, but power consumption increases
Solution Approach 1:
The patent substitutes power-intensive digital circuitry with a low-power analog differentiator circuit. The analog implementation using passive components and a single operational amplifier consumes significantly less power while delivering the same EMI reduction performance through continuous analog signal processing rather than discrete digital operations
3Device complexity
If simple analog implementations are used, then device simplicity and low power consumption are achieved, but EMI reduction performance deteriorates
Solution Approach 1:
The analog differentiator circuit is self-sufficient in generating the required modulation waveform. It automatically produces the frequency deviation signal needed for spread spectrum modulation by differentiating the control voltage, eliminating the need for additional complex waveform generation circuitry while maintaining effective EMI reduction
Solution Approach 2:
The patent achieves effective EMI reduction with simple analog circuitry by changing the modulation approach to use analog differentiation. This parameter change in the modulation technique allows the simple differentiator circuit to generate the necessary frequency variations for spread spectrum, achieving both simplicity and performance
Data Source
AI summary
A spread spectrum clock generator which includes a pulse train generator circuit and a modulating circuit configured to produce a modulating signal relating to a time derivative of an output of the pulse train generator circuit. In one embodiment the modulating circuit includes a active differentiator circuit and in another embodiment the modulating circuit includes a passive differentiator circuit. A modulator is included which is configured to produce a spread spectrum clock output which is frequency modulated by the modulating signal.