Stacked-chip implementation of on-chip buck converter for distributed power supply system in sips

Abstract

An on-chip buck converter which is implemented by stacking chips and suitable for on-chip distributed power supply systems is proposed. The operation of the converter with 3-D chip stacking is experimentally verified for the first time. The manufactured converter achieves a maximum power efficiency of 62% for an output current of 70 mA and a voltage conversion ratio of 0.7 with a switching frequency of 200 MHz and a 2 × 2 mm on-chip LC output filter. The active part and the passive LC output filter are implemented on separate chips fabricated in 0.35- μm CMOS and connected with metal bumps. The use of glass epoxy interposer to increase the maximum power efficiency up to 71.3% is also discussed. © 2007 IEEE.