Patent ID: 8327163

Claim:
An apparatus for providing a virtual power supply to a circuit portion of an integrated circuit, comprising: a plurality of power switches coupled in at least two independent chains between a plurality of VDD conductors coupled to a power supply and virtual VDD conductors providing the virtual power supply, having control signals coupled in sequence to an enable signal to sequentially turn on; the plurality of VDD conductors disposed over the circuit portion and arranged in parallel to one another and extending in a first direction: a plurality of the virtual VDD conductors disposed over the circuit portion arranged in parallel to one another and extending in a second direction different from the first direction and intersecting at least two of the VDD conductors, each of the plurality of virtual VDD conductors coupled to at least two of the power switches coupled in at least two independent chains; and an enable control circuit providing enable signals to the chains at predetermined times; wherein the virtual power supply is provided on the virtual VDD conductors coupled to each of the power switches, and the power switches in the independent chains are configured so that the virtual VDD conductors may receive the virtual power supply even if a break in one of the independent chains occurs, and the portion of the circuit is powered on by enabling the power switches.