An efficiency-enhanced asynchronous buck converter with threshold compensated freewheeling diode

We present in this paper the design of an integrated asynchronous buck converter with improved power conversion efficiency. A threshold compensated freewheeling diode is introduced to the converter to minimize both the diode forward voltage drop as well as the reverse leakage current. In order to enable monolithic high voltage switching, serially stacked MOS transistors are utilized. The buck converter is implemented in a 65nm CMOS technology. In simulation, with 2.5V input voltage and 10 MHz switching frequency, 85% power conversion efficiency can be achieved for a load current of 10mA at 1.2V output voltage. As compared to a standard asynchronous implementation, the overall dissipation in the power stage can be improved by more than 30%.