What is the difference between AOCV and POCV?

POCV is more realistic approach than that of OCV and AOCV. This method does not use distance and depth based derate factor. It uses delay sigma to model the delay variation of the cell. In POCV instead of applying the specific derate factor to a cell, cell delay is calculated based on delay variation (σ) of the cell.

What is systematic variation in VLSI?

Systematic variation: Systematic variations are deterministic in nature and are caused by the structure of a particular gate and its topological environment. The systematic variations are the component of variation that can be attributed to a layout or manufacturing equipment related effects.

What is liberty variation format?

What is Liberty Variation Format (LVF) and how does it impact timing? LVF is an extension to the Liberty format that adds statistical variation information to timing measurements. LVF extends that information with additional tables for early and late statistical variation (sigma) values of each measurement.

What is SOCV?

Statistical OCV (SOCV) is a simplified approach to SSTA that uses a single local variable. It solves the major limitations of AOCV, including variation dependency on slew and load, and the assumption that the same cell, or load, is in the path. You compress everything into one variable and that’s your statistical OCV.”

When to use 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,…

What is the variation of OCV for launch?

OCV variation is +8% and -9% and one of them will be used for launch and other for capture in setup/hold timing calculations. For eg. for setup calculation, the launch clock will have OCV of +8% and capture clock path will have OCV of -9%.

Is the OCV effect modelled as random variation?

OCV effects are modelled as random variation. OCV has a relatively small impact at larger process nodes (e.g., 130/90nm) and can be modelled using a single derating value per cell (or even per design). More granularity is required as lower process nodes.

How does timing verification model the OCV effect?

Since the clock and data paths can be affected differently by the OCV, the timing verification can model the OCV effect by making the PVT conditions for the launch and capture paths to be slightly different. In STA one can model these variations by derating the delays of specific paths i.e by making path slower or faster as per the need.