Sage-Tips

Which of the following is considered as a false timing path?

An example (of a false path) is a register that might be written once on power up, but then remains in the same state. Simply, a false path is a logic path that you want excluded from being checked to see if it meets timing during timing analysis.

What is false path how it is determined in circuit?

A false path (FP) occurs when there is a traceable path through a design that is never enabled. Either the design itself or the way the design is used ensures that the path will not be exercised. Figure 2 shows a design in which all valid paths go through a section of slow logic and a section of fast logic.

What are false paths in VLSI?

False paths: False paths are those timing arcs in the design where changes in source register (flop) are not required to capture at the destination register. The timing path in these topologies can’t be sensitized by any input vector even if both source and destination flops are using same clock source.

What is set false path?

Specifies a false-path exception, removing (or cutting) paths from timing analysis. The -from and -to values are collections of clocks, registers, ports, pins, or cells in the design. Applying exceptions between a pair of clocks is more efficient than for specific node to node or node to clock paths. …

Which are 4 different timing paths in static timing analysis?

Types of Paths for Timing analysis: Data Path. Clock Path. Clock Gating Path.

What are clock tree exceptions?

Clock Tree Exceptions Non- Stop Pin. Exclude Pin. Float Pin. Stop Pin. Don’t Touch Subtree.

What is half cycle path in VLSI?

What is a half cycle path? A half cycle timing path is one in which launch and capture happen on different clock edges. A half cycle path can be in terms of both setup and hold. However, normally, in technical terms half cycle path is the one which has setup check getting formed as half cycle.

What are timing exceptions in VLSI?

Timing exceptions allow you to modify the default timing analysis rules for specific paths, such as multicycle paths, false paths, and minimum and maximum delays.

What are timing paths in VLSI?

Timing path is defined as the path between start point and end point where start point and end point is defined as follows: Start Point: All input ports or clock pins of a sequential element are considered as valid start point.

How do you calculate path delay?

Path delay = Cell delay + Net delay. As there are multiple ways for the logic to propagate from one start point to an end point (Figure 5), the maximum and minimum timing paths can be calculated easily based on cell delay and net delay.

What are clock tree exceptions in VLSI?

Clock Tree Exceptions

• Non- Stop Pin.
• Exclude Pin.
• Float Pin.
• Stop Pin.
• Don’t Touch Subtree.
• Don’t Buffer Nets.
• Don’t Size Cells.

What is a false path in software testing?

The timing path resulting in such scenarios is labeled as false path and is not optimized for timing by the optimization tool. Definition of false path: A timing path, which can get captured even after a very large interval of time has passes, and still, can produce the required output is termed as a false path.

Do false paths need to be timed in timing analysis?

A false path, thus, does not need to get timed and can be ignored while doing timing analysis. Synchronized signals: Let us say we have a two flop synchronizer placed between a sending and receiving flop (The sending and receiving flops may be working on different clocks or same clock).

What is false path in a microcontroller?

False path is a very common term used in STA. It refers to a timing path which is not required to be optimized for timing as it will never be required to get captured in a limited time when excited in normal working situation of the chip.

What is an invalid path in static timing analysis?

But the static timing analysis tool will not consider this as an invalid path, it just looks for valid timing arcs, an there is a timing arc from B input to output of the first mux and then to the Y signal through the second mux. This is just a simple example of a false path. There can be many paths of this type in a large design.