A slew-rate based process monitor and bi-directional body bias circuit for adaptive body biasing in SoC applications

Abstract

A process monitor based on slew-rate measurement has been applied to a body bias control system to detect the process corners and adjust the body bias voltage necessary to meet the power and performance requirements for CMOS circuits. The process monitor consists of N- and P- type slew generators, pulse generator, pulse extender, counter and control circuits. A new analog pulse extender has been developed to increase the pulse width for easy characterization of process corners in practical systems. Circuit description, design considerations, and measured results of the process monitor and body bias generator circuits in 55nm CMOS process are presented. Active circuit area for the process monitor and body bias generator are 0.023 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 0.013 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and power dissipation for process monitor and bias generator are 400 μW and 55 μW using a 0.9 V supply. Measured silicon results match with simulation results and show correct operation of the circuits.