What is a multicycle path?

A Multicycle path in a sequential circuit is a combinational path which doesn’t have to complete the propagation of the signals along the path within one clock cycle. For a Multicycle path of N, design should ensure the signal transition propagated from source to destination within N clock cycle.

What is multicycle path in VLSI?

Definition of multicycle paths: By definition, a multi-cycle path is one in which data launched from one flop is allowed (through architecture definition) to take more than one clock cycle to reach to the destination flop.

How do you set a multicycle path?

Answer: To set a multicycle maximum path, you can either move the end clock forward or the start clock backward. To set a multicycle minimum path, you can either move the end clock backward or the start clock forward.

What is asynchronous path in VLSI?

Asynchronous path: A path from an input port to an asynchronous set or clear pin of a sequential element. See the following fig for understanding clearly. Timing Path- Asynchronous Path. As you know that the functionality of set/reset pin is independent from the clock edge.

What is false path multicycle path?

False paths: These are paths in a design that exist but changes in source register are not required to be captured at the destination register within one clock cycle. Multi-Cycle paths: Paths where data is not required to reach the capture flop within one clock cycle.

What is Set_false_path?

set_false_path is a point-to-point timing exception command. This means. it assists in overriding the default single-cycle timing relationship. for one or more timing paths. Other point-to-point timing exception.

What is CRPR in VLSI?

The delay difference along the common paths of the launching and capturing clock paths is called CRPR.

What does Set_false_path mean?

The set_false_path command disables timing from path startpoints. through path throughpoints to path endpoints. Path startpoints are. input ports or register clock pins.

What is timing path 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. End Point: All output port or D pin of sequential element is considered as End point.

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.

How do you identify a false path?

A path is a sequence of logic elements through which data can propagate, bounded by either ports or registers. A path is false if no sequence of input vectors can result in an event propagating along it. Such paths may be ignored for timing analysis purposes.

How do I set a hold multicycle path of 1?

1. set_multicycle_path -start: This will cause a cycle of launch clock to be added in setup check. As expected, on applying a hold multicycle path of 1, the hold will return back to 0 cycle check. Figure 7 below shows the effect of below two commands on setup and hold checks.

How are multi-cycle paths handled in Sta?

How multi-cycle paths are handled in STA: By default, in STA, all the timing paths are considered to have default setup and hold timings; i.e., all the timing paths should be covered in either half cycle or single cycle depending upon the nature of path (see setup-hold checks part 1 and setup-hold checks part 2 for reference).

How do I specify the multicycle paths to synthesis and place&route tools?

It is important to specify the multicycle paths to synthesis and place&route tools, as the tools will otherwise try to fix these paths. This timing exception is specified by the SDC command “set_multicycle_path”. This lets you specify the number of clock cycles required for the path. Let us take the timing path from the previous post Setup & Hold.

What is the difference between a false and multicycle path?

Unlike false paths, multicycle paths are valid and must be analyzed, but against more than one clock period. Consider an example as shown in Figure 1, where we have only one clock (of 2ns period) in our design and we are performing a 64-bit addition of two buses. The input buses to the adder, as well as the output bus from the adder are registered.