What is CPPR adjustment?

For Pessimism no need of derating for late(Max delay path) in setup and early (Min delay path) in hold Analysis. …

How is static timing analysis done?

Static timing analysis (STA) is a method of validating the timing performance of a design by checking all possible paths for timing violations. Another way to perform timing analysis is to use dynamic simulation, which determines the full behavior of the circuit for a given set of input stimulus vectors.

What is common path pessimism?

When any pair of launching and capturing flop have a some portion of clock path as common, the difference between the max and min delay of that common clock segment is referred to as Common Path Pessimism.

What is AOCV and POCV in VLSI?

In this article, A comparative study of OCV (On Chip Variation), AOCV (Advance On Chip Variation) and POCV (Parametric On Chip Variation) have been done. Why and how a new variation model has evolved over the previous one and how it is better in term of timing pessimism have also been discussed.

What is timing derate?

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.

What are clock path timing checks?

It’s very important to understand this clearly to understand and analysing the Timing analysis report and fixing the timing violation. Data path. Start Point. Input port of the design (because the input data can be launched from some external source). Clock pin of the flip-flop/latch/memory (sequential cell)

Why do we need static timing analysis?

The main goal of static timing analysis is to verify that despite these possible variations, all signals will arrive neither too early nor too late, and hence proper circuit operation can be assured. Since STA is capable of verifying every path, it can detect other problems like glitches, slow paths and clock skew.

Why static timing analysis is required?

How do you do static timing?

The number of degrees varies from car to car (again consult the handbook). Static timing means setting the timing with the engine stopped. You set the crankshaft at the correct number of degrees before top dead centre, then adjust the distributor by turning it until the contact-breaker points are just opening.

What is clock pessimism?

The clock pessimism shows the absolute amount of extra clock skew introduced by the fact that source and destination clocks are reported with different types of delay even on their common circuitry. In reality, it is not possible for common circuitry to be analyzed with 2 different delays at the same time.

Why is POCV better than AOCV?

POCV was proposed to address shortcomings of AOCV/SBOCV for granularity, accuracy, Common path pessimism removal and half cycle paths. POCV eliminates the need for stages, path type and corner delay to find delay derate during characterization phase.

What is the CPPR for launch and capture timing?

The skew across launch and capture comes out to be 110-90 = 20ps. Hence ideally, the tool should adjust this as a CPPR of 20ps in timing calculations but this does not happens. In most cases, the tool considers a default threshold of minimum uncommon and/or common path delay to be considered for each path.

What does CPPR stand for?

Common Path Pessimism Removal (CPPR) A timing path consists of launch and capture paths. The launch path has further components – the launch clock path and the data path. In the above circuit snippet, the launch path is c1->c2->c3 -> CP-to-Q of FF1 -> c5 -> FF2/D

Do common clock paths have two different delays for timing analysis?

However, part of the clock paths is common, till node n1. It is not realistic that these have two different delays for the same analysis. Using the late and early timing numbers for the common path creates unwanted pessimism in timing analysis leading to difficulties in timing closure or overdesign.

What is timing analysis in timing engineering?

Timing analysis for this case would depend on the clock architecture that the design is intended to support. For setup analysis, the most pessimistic check would be if launch is through the longest clock path and capture is through the shortest clock path. Timing engineers need to make sure if such paths are supported by the architecture.