Delta-sigma modulator based compact sensor signal acquisition front-end system

• Main Authors: Basu, Joydeep, Mandal, Pradip
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering::Electrical and electronic engineering; Physics - Instrumentation and Detectors; Analog Front-End; Analog to Digital Conversion ADC
• Online Access: https://hdl.handle.net/10356/153965
• Institution: Nanyang Technological University

The proposed delta-sigma modulator (△ΣM) based signal acquisition architecture uses a differential difference amplifier (DDA) customized for dual purpose roles, namely as instrumentation amplifier and as integrator of △ΣM. The DDA also provides balanced high input impedance for signal from sensors. Further, programmable input amplification is obtained by adjustment of △ΣM feedback voltage. Implementation of other functionalities, such as filtering and digitization have also been incorporated. At circuit level, a difference of transconductance of DDA input pairs has been proposed to reduce the effect of input resistor thermal noise of front-end R-C integrator of the △ΣM. Besides, chopping has been used for minimizing effect of Flicker noise. The resulting architecture is an aggregation of functions of entire signal acquisition system within the single block of △ΣM, and is useful for a multitude of dc-to-medium frequency sensing and similar applications that require high precision at reduced size and power. An implementation of this in 0.18-μm CMOS process has been presented, yielding a simulated peak signal-to-noise ratio of 80 dB and dynamic range of 109 dBFS in an input signal band of 1 kHz while consuming 100 μW of power; with the measured signal-to-noise ratio being lower by about 9 dB.