Stacked-chip Implementation of On-Chip Buck Converter for Power-Aware Distributed Power Supply Systems

An on-chip buck converter which is implemented by stacking chips and which is suitable for on-chip distributed power supply systems is proposed and the operation is experimentally verified for the first time. The manufactured converter achieves the maximum power efficiency of 62% for an output current of 70 mA with a switching frequency of 200 MHz with a 2times2 mm on-chip LC output filter. The active part and the passive LC output filter are implemented on separate chips fabricated in 0.35-mum CMOS and connected with metal bumps. The optimization and improvement of the power efficiency and implementation structure are also discussed.