Introduction and Overview
Clock frequency is a major attribute of any microprocessor design. Early on, during product definition, it constitutes a major business or marketing decision and it is usually the result of a trade-off among customer needs, competitive landscape, and time-to-market. As soon as the frequency target is handed down the food chain to silicon implementation, it will affect all project design aspects from the day that the project is kicked off until it tapes out (and in most cases well beyond this point too). It is not surprising therefore that the job of generating, distributing, and analyzing the clocks in complex chips is considered to be an important and visible assignment. Clock design has traditionally been an area of innovation and has been in the spotlight in technical conferences and journals.
Why is clock frequency such an important microprocessor aspect? For a number of applications it is only loosely correlated with performance with other design aspects such as memory system, parallelism, and hardware acceleration being equally or even more effective. Nevertheless, it is a single number that is widely understood by both technical and nontechnical audiences and in certain situations has strong correlation with single-thread performance.
KeywordsPhase Noise Clock Generation Clock Frequency Clock Distribution Server Processor
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