A high efficiency DC-DC converter using 2nH on-chip inductors

Historically buck converters have relied on high-Q inductors on the order of I to 100 mu H to achieve high efficiency. In this paper we exploit on-chip magnetic coupling in the proposed stacked interleaved topology to enable high efficiency buck converters to be realized with 2nH moderate-Q on-chip inductors. The measured conversion efficiency for a prototype circuit implemented in a 130-nm CMOS technology was over double that of a linear converter for low output voltages rising to a peak value of 77.9% for a 0.9V output.