Supplying a clock signal and a gated clock signal to synchronous elements

摘要

A clock gating circuitry is configured to receive a clock signal and to output an output signal comprising either the clock signal or the predetermined gated value. The circuitry receives a clock signal, a clock enable signal having either an enable value or a disable value, and a power mode signal having either a low power value (indicating entry to a low power mode in which at least a portion of the plurality of synchronous elements are powered to retain data and are not clocked and at least a further portion of the plurality of synchronous elements are powered down), or a functional mode value (indicating the plurality of synchronous elements are to be powered). A clock gating unit has logic circuitry that is configured to output the clock signal or the predetermined gated value depending upon the low power value and the functional mode value.