An advanced power system in package (SiP) for voltage regulators is presented; it offers the world's lowest power dissipation of 4.4 W at 1 MHz, with an output voltage of 1.3 V and an output current of 25 A. Its package resistance is 88% lower due to using Cu leads for the bonding, which reduces the spreading resistance of the MOSFET. The diode loss is 43% lower due to using a Schottky barrier diode incorporated into the low-side MOSFET. The thermal resistance is also 43% lower due to using a large topside Cu lead.