A New Process Variation Monitoring Circuit

Abstract

A new process variation monitoring circuit (PVMC) has been proposed in the paper. The goal is to generate a digital signal/code which (code value) will characterize the process corner. The circuit uses only metal-oxide-semiconductor (MOS) transistors to detect variation of their parameters, or process corner by generating digital signals. Process variation is detected based on variation of parameters of n-type MOS transistor, such as threshold voltage, oxide thickness. Proposed circuits' operation is based on a method called “dynamic measurement”, which enables to monitor process variation or corner by using only one type of transistors (n-type or p-type). Absence of devices such as bipolar transistors, diodes and resistors, reference voltage or current (or other parameters) sources leads to increase in detection accuracy and simplicity, as well as circuit area and current reduction. Post-layout simulation results prove correct functionality of the proposed circuit. Although proposed circuit detects process variation/corner by dealing with parameters of n-type MOS transistors, it can be easily modified to include/detect variation of also p-type MOS transistors, resistors or other components.