A DLL-based Body Bias Generator for Minimum Energy Operation with Independent P-well and N-well Bias

This paper proposes an area- and energy-efficient DLL-based body bias generator (BBG) for minimum energy operation that controls p-well and n-well bias independently so that the BBG can minimize total energy consumption under a skewed process condition between nMOSFETs and pMOSFETs. The proposed BBG is composed of digital cells compatible with cell-based design, which results in low energy consumption and small area. A test circuit is implemented in a 65-nm FDSOI process. Measurement results using a 32-bit RISC processor implemented on the same chip show that the proposed BBG can reduce energy consumption close to a minimum where the amount of excess energy is 3%. In this condition, energy and area overheads of the BBG are 0.2% and 0.12%, respectively.