US Patent 7577052 Power switching circuit

A power control circuit for an integrated circuit module includes at least one switch device coupled between a supply voltage and a power node of the integrated circuit module; and a switch control module having a first terminal coupled to the switch device, a second terminal coupled to a control signal, a third terminal coupled to a first storage node of at least one tracking cell, a fourth terminal coupled to a second storage node of the tracking cell, and a fifth terminal coupled to the power node of the integrated circuit module, for controlling the switch device to pass the supply voltage to the power node with or without a substantial voltage drop depending on an operation mode of the integrated circuit module.