The Significance of Clock Signals
The clock distribution network is responsible for distributing the clock signal(s) from a central point to all the elements that require it. Due to its vital function, it is essential to understand the characteristics of clock signals and the electrical networks involved in their distribution. In this article, we will explore the significance of clock distribution networks in synchronous systems and delve into the unique attributes of clock signals.
Clock signals, despite being commonly perceived as simple control signals, possess distinctive characteristics and attributes that differentiate them from other signals in a synchronous system. Let’s examine some of the reasons why clock signals hold such importance:
Fanout and Distance
Clock signals typically have the highest fanout and travel over the longest distances compared to any other signal within the system, be it control or data. They are responsible for synchronizing the timing of various components and ensuring the proper functioning of the system.
Clock signals operate at the highest speeds among all signals within the synchronous system. As they provide a temporal reference for the data signals, it is importantthat the clock waveforms are clean and sharp to accurately synchronize the data transfers.
Impact of Technology Scaling
Clock signals are particularly affected by technology scaling, as described by Moore’s law. With decreasing line dimensions, long global interconnect lines become significantly more resistive, increasing line resistance. This phenomenon emphasizes the importance of clock distribution in maintaining synchronous performance.
Clock Skew and Uncertainty
Differences and uncertainty in the arrival times of clock signals can severely limit the maximum performance of the entire system and lead to catastrophic race conditions. When clock signals are not synchronized properly, incorrect data signals may latch within a register, resulting in erroneous operation.
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