Development of a Self-Correcting CMOS-Based Clock Generator for Wireless Sensor Network in 90nm Process Technology

Abstract

The trend in today’s technology is continuously evolving and resolving some of the nature’s problems through environmental monitoring. Sensor platforms are acquainted to these functions, for it is one of the devices that enables the reading of data from the environment and interprets to a function that allows monitoring. In every sensor platform, a stable clock generator circuit is a necessity to synchronize the input data from the output results and action. A self-correcting clock generator fixes the process, voltage, and temperature variation issues that affect the outputs of almost all clock generator circuit. The Five-stage Prescriptive Model was used to have a proper procedure in designing the clock generator while pairwise comparison chart and decision matrix were used for the evaluation of alternatives. Current starved ring oscillator was the main circuit block that was used as clock generator which produced the desired frequency. Different circuit blocks such as frequency to voltage converter, analog to digital converter, limiter circuit, trimming circuit, and oscillator are put together as the feedback circuit. The clock automatically corrects itself with a frequency variation of ±10% even if the process, voltage, and temperature change. This study focused on having a low power of 1.12mW for the whole circuit, with a voltage supply of 1.2V. It has three different output frequencies, 26MHz, 13MHz, and 1.08MHz, that were obtained using frequency dividers. The design was implemented using Synopsys tool in 90nm CMOS process technology.