A Reconfigurable Monolithic 3D Switched-Capacitor DC-DC Converter with Back-End-of-Line Oxide Channel Transistor

A monolithic three-dimensional (M3D) switched-capacitor (SC) DC-DC converter is proposed that leverages the back-end-of-line (BEOL) compatible tungsten-doped indium oxide (IWO) transistor. The M3D SC allows placing the voltage converter on top of CMOS circuits at the interconnect level to perform the fine-grain voltage regulation for different circuit blocks. This work designs a two-stage reconfigurable SC circuit with BEOL integrated IWO transistor and capacitors to provide a wide range of conversion ratios (4:1, 3:1, 9:2, and 6:1). A peak efficiency of 84% at 1 mW/mm
²
is achieved for a 4:1 conversion ratio. In addition, the M3D SC DC-DC converter is utilized to enable dynamic voltage frequency scaling (DVFS) in the systolic array in a TPU-like architecture. The proposed DVFS scheduling reduces the energy consumption of the systolic array by 9% on the deep neural network inference workloads, with an increase of 3% in maximum computation time.