3D-structured on-chip buck converter for distributed power supply system in SiPs

An on-chip buck converter with 3D chip stacking is proposed and the operation is experimentally verified. The manufactured converter achieves a maximum power efficiency of 62% for an output current of 70mA with a switching frequency of 200MHz and a 2x2mm on-chip LC output filter in 0.35μm CMOS. The use of glass epoxy interposer to increase the maximum power efficiency up to 71.3%, and the power efficiency dependence on the filter inductor are also discussed.