24 August 2013

Setup and hold slack


13.    Setup and hold slack

Slack
Slack is defined as difference between actual or achieved time and the desired time for a timing path. For timing path slack determines if the design is working at the specified speed or frequency.



04 August 2013

Setup and hold time definition


12.    Setup and hold time definition

Setup and hold checks are the most common types of timing checks used in timing verification. Synchronous inputs (e.g.  D)  have Setup, Hold time specification with respect to the clock input. These checks specify that the data input must remain stable for a specified interval before and after the clock input changes

 

Ø  Setup Time:  the amount of time the data at the synchronous input (D) must be stable before the active edge of clock

Ø  Hold Time: the amount of time the data at the synchronous input (D) must be stable after the active edge of clock.


Both setup and hold time for a flip-flop is specified in the library.

Fundamentals of Timing


1.    Fundamentals of Timing

11.1. Timing paths

Any digital circuit can be represented as a “timing path” modeled between two flip flops.