Clock gating for scan shift clock in a mesh clock environment

Abstract

Clock distribution circuitry, for distributing clocks for scan operations in an integrated circuit device in which a mission mode clock is distributed by a mesh clock structure and a scan fabric clock is distributed by a scan clock bus, includes a mesh clock source, and a local distribution structure for distributing the clocks for scan operations to a local clock domain that includes a subset of taps of the mesh clock structure. The local distribution structure includes a local controller for controlling derivation of a scan capture clock from the mesh clock source, local scan host circuitry for deriving a local scan shift clock from the scan fabric clock, and specialized integrated clock gates corresponding in number to the subset of taps of the mesh clock structure, for selecting between the scan capture clock in a scan capture mode, and the local scan shift clock in a scan shift mode.