A Multiphase Synchronous Buck Converter With a Fully Integrated Current Balancing Scheme

A multiphase synchronous buck converter has been developed, in which the number of switching phases is determined by the sensed average load current. The maximum number of switching phases is four. The dc resistance (DCR) of switching inductor is used to detect the average current, which is also utilized to balance the load current among the multiple switching phases. The instantaneous inductor current is sensed as well to generate the pulsewidth modulation (PWM) signal to switch the inductors. The multiphase synchronous buck converter implemented in a 0.13-μm BCDMOS process shows 91.1% maximum power efficiency when the input voltage is 2.8 V, output voltage is 1.0 V, and output current is 2.0 A.