Low-power CMOS circuit design of audio frequency shift keying for emergency alert system

Abstract

Emergency alert systems are highly essential during natural disasters like earthquake, flooding, volcanic eruption, landslides and hurricanes to make the public alert. Existing emergency alert systems use siren, text alert and broadcasting, but they are slow and may not alert at the right time in crucial situations. An Audio Frequency Shift Keying (AFSK) is designed to alert the public in emergency without hearing the text of the alert. It is designed with low power relaxation oscillator and voltage-controlled oscillator using CMOS technology. In this work, a relaxation oscillator is designed with inductor-less circuit for wideband tuning and provides huge area saving in the design. The control unit is designed to select the audio signal with two different oscillation frequencies based on input data. The public would be able to get awareness about the condition of natural disaster based on frequency of audio signal. An AFSK is designed with an operating voltage of 400 mV that consumes only 6.18 µW of power while implementing using 180 nm CMOS technology.