Ultra-low power delta–sigma modulator for biomedical application

The electronics of a general biomedical device consist of energy delivery, analog-to-digital conversion, signal processing, and communication subsystems. Each of these blocks must be designed for minimum energy consumption. This paper presents the design of a delta-sigma modulator for analog to digital converter (ADC) for bio medical application.This delta-sigma modulator design is paid special attention to its low power application of portable electronic system in digitizing biomedical signals such as pacemaker which detects and assists the heart’s natural electrical activity. The delta-sigma architecture is implemented as third-order distributed feed forward delta-sigma modulator; by using this implementation can reduce the power consumption. Additionally, the use of transistors in weak inversion region saved power. The designed modulator has consumed only 712nW for 250 Hz bandwidth. The dynamic range of this designed modulator is 53dB. The core chip size is 1mm2 by using the 0.18μm standard CMOS process.

Keywords:

Delta–sigma modulator , Switched-capacitor circuit , biomedical circui , Oversampling , Analog-to digital converter (ADC) , Analog circuit desig , ultra low-power circuits