Pulse Width Checks - 2021.2 English

Vivado Design Suite User Guide: Design Analysis and Closure Techniques (UG906)

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2021.2 English

The pulse width checks are some rule checks on the signal waveforms when they reach the hardware primitives after propagation through the device. They usually correspond to functional limits dictated by the circuitry inside the primitive. For example, the minimum period check on a DSP clock pin ensures that the clock driving a DSP instance does not run at higher frequency than what is tolerated by the internal DSP.

The pulse width checks do not affect synthesis or implementation. Their analysis must be performed once before the bitstream generation like any other design rule check provided by the Vivado Design Suite.

When a pulse width violation occurs, it is due to an inappropriate clock definition (pulse width and period checks) or an inappropriate clock topology that induces too much skew (max_skew check). You must review the Xilinx FPGA data sheet of the target device to understand the operation range of the primitive where the violation occurs. In the case of a skew violation, you must simplify the clock tree or place the clock resources closer to the violating pins.