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Spread-spectrum clock generation (SSCG) is used in some synchronous digital systems, especially those containing microprocessors, to reduce the spectral density of the electromagnetic interference (EMI) that these systems generate.
A spread-spectrum clock (CLK) is an efficient way to reduce EMI. This article describes how the spread-spectrum CLK is defined, and provides a simple formula for estimating the EMI suppression. The resulting formula is verified by data generated by the Maxim CLK Generation chip, MAX9492.
1 de feb. de 2004 · The idea behind using a spread spectrum technique to reduce EMI is to keep the clock moving. A steady clock is an easy target for neighboring devices and conformity test equipment to lock onto, allowing them time to accumulate emanating signal energy at the fixed clock frequency or its harmonics.
Spread spectrum clocking is a technique where the clock frequency is modulated slightly to lower the peak energy generated by a clock. Spread spectrum clocking lowers clock-generated EMI from both the fundamental frequency and subsequent harmonics, thereby reducing the total system EMI.
18 de feb. de 2003 · The formal definition of spread spectrum is more precise: an RF communications system in which the baseband signal bandwidth is intentionally spread over a larger bandwidth by injecting a higher frequency signal (Figure 1).
A spread-spectrum phase-locked loop (PLL) clock generation system is modeled and simulated using Simulink. A multi-phase voltage-controlled oscillator (VCO) along with a delta-sigma modulator is used for spreading with a triangular signal of 33 kHz frequency for an output frequency of 3 GHz.
Spread spectrum clocking is a technique used in electronics design to intentionally modulate the ideal position of the clock edge such that the resulting signal’s spectrum is “spread”, around the ideal frequency of the clock.
