An optimal power supply and body bias voltage for a ultra low power micro-controller with silicon on thin box MOSFET

Body bias control is an efficient means of balancing the trade-off between leakage power and performance especially for chips with silicon on thin buried oxide (SOTB), a type of FD-SOI technology. In this work, a method for finding the optimal combination of the supply voltage and body bias voltage to the core and memory is proposed and applied to a real micro-controller chip using SOTB CMOS technology. By obtaining several coefficients of equations for leakage power, switching power and operational frequency from the real chip measurements, the optimized voltage setting can be obtained for the target operational frequency. The power consumption lost by the error of optimization is 12.6% at maximum, and it can save at most 73.1% of power from the cases where only the body bias voltage is optimized. This method can be applied to the latest FD-SOI technologies.