What are on chip variations?
On-chip variation (OCV) is a recognition of the intrinsic variability of semiconductor processes and their impact on factors such as logic timing.
What is OCV and AOCV?
AOCV stands for Advanced OCV and SBOCV stands for Stage Based OCV. To clarify the need for AOCV, consider two cases of single and multiple cells. Single cell in isolation exhibits larger delay variation compared to number of cells in a path.
Why are Derates applied?
On chip Variation (OCV): In OCV a fixed timing derate factor is applied to the delay of all the cells present in the design so that in case of process variation affects the delay of any cells during the fabrication, it will not affect the timing requirements and the chip will not fail after fabrication.
What is POCV coefficient?
The coefficient is the value of the variation at 1 standard deviation from the nominal delay. Monte Carlo analysis is used to get the POCV coefficients. There is only one value of C for each timing arc of the cell irrespective of the input transition and output load.
What is systematic variation and random variation?
Random variations refer to random fluctuations in parameters from die to die and device to device. Systematic variations refer to layout-dependent variations that cause nearby devices to share similar parameters.
What is CRPR and CPPR in VLSI?
CPPR: CRP and CRP removal (CRPR) are often used synonymously with CPPR; however, CRPR and CPPR should not be confused to be one and the same but rather two completely different perspective of clock path pessimism. CPPR is primarily due to OCV variations while CRPR is an architectural artifact.
What is derating in Sta?
Abstract: Derating is a versatile technique supported by all static timing analysis (STA) tools in industry. In essence, it enables designers to modify any delay or slew computation performed by such tools. Despite this common use in industry, the scientific literature on derating is scarce to none.
What is a derating analysis?
Derating Analysis is a product reliability test that helps determine if there are any underspecified components in a product.
What is LVF in VLSI?
LVF is an extension to the Liberty format that adds statistical variation information to timing measurements. Nominal timing libraries contain numerous lookup tables that include timing information such as cell delays, transition times and setup and hold constraints for all cells in the library.
What is CRPR?
OCV (On Chip Variation) and CRPR (Clock Reconvergence Pessimism Removal)
What is the difference between random variation and non random variation?
In a random process we cannot know the exact value of the next outcome, but from studying previous data we may predict the probability of future outcomes. So, a random process is predictable. Non-random variation, on the other hand, appears when something new, sometimes unexpected, starts to influence the process.
What is systematic variation?
In research and experimental situations, the term systematic variation generally denotes an anomaly or inaccuracy in observations which are the result of factors which are not under statistical control.
What is CRP in VLSI?
CRP is the difference between the max and min delay of the common path. This is the value which indicate how much is the pessimism. ( Means worst possible outcome).
What is skew in VLSI?
It’s a difference between the clock arrival time across the chip. It’s the time delta between the actual and expected arrival time of a clock signal. Clock skew is the timing differences between signals in a clock distribution system.
What is a derating factor?
What is Derating factor in cable sizing? De-rating factor, also known as correction factor, is a multiplier that is applied to a cable ampacity rating in order to change the value depending on various operation conditions. For example ambient air temperature, soil temperature and laying method of the cable.
What is called derating?
In electronics, derating (or de-rating) is the operation of a device at less than its rated maximum capability in order to prolong its life. Typical examples include operation below the maximum power rating, current rating, or voltage rating.
How is CRPR calculated?
CRPR = Max. In the CRPR process we are removing the derating to common buffer. here the common buffer buf1.so we are considering 0.70ns-. 60ns =. 10ns for buf1.
What is random and systematic variation?
What is on-chip variation in static timing analysis?
And On-Chip Variation (OCV) is one of them, specifically for Static Timing Analysis. The first task is to find all possible sources variation, and find out how these can affect a delay of a cell and hence, timing. In this article I will focus on the various sources of on chip variation:
What is on-chip variation (OCV)?
On Chip Variation (OCV) is an increasing problem that starts at 130nm and its effects are increasing with smaller process nodes. And On-Chip Variation (OCV) is one of them, specifically for Static Timing Analysis. The first task is to find all possible sources variation, and find out how these can affect a delay of a cell and hence, timing.
What is parametric on-chip variation (pocv)?
To address the shortcomings of AOCV, parametric on-chip variation (POCV) evolved. In POCV, instead of applying a specific derating factor to a cell, cell delay is calculated based on a delay variation of that cell. This delay variation ( σ ) for each cell is obtained through Monte-Carlo HSPICE simulation.
What drives the timing variation in ICS?
Historically, as well as operating temperature, timing variation was primarily a consequence of subtle shifts in manufacturing conditions that would lead to ICs from one batch of wafers being ‘slow’ or ‘fast’ relative to nominal estimates.