An untrimmed CMOS amplifier with high CMRR and low offset for sensor applications

• Main Authors: Zhang, Xiao Ling, Chan, Pak Kwong
• Other Authors: School of Electrical and Electronic Engineering
• Format: Conference or Workshop Item
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Electronic circuits
• Online Access: https://hdl.handle.net/10356/90453; http://hdl.handle.net/10220/6364
• Institution: Nanyang Technological University

This paper presents a new CMOS amplifier with high common-mode rejection ratio (CMRR) and low offset, dedicated to integrated sensors, using total continuous-time design technique but without the need of trimming. This is based on cascading two high-gain differential stages to form a composite front-end gain stage for enhancing CMRR as well as reducing systematic errors, and incorporating an averaging layout technique to reduce the random mismatch errors. Powered by a total 3.3V supply, measurements on 15 samples have shown that the mean and standard deviation of the input-referred offset are 50.4μV and 0.678mV respectively. The proposed amplifier has also achieved CMRR greater than 110dB (0 - 150Hz), offset drift less than 0.8 μV/oC for temperature ranging from –55oC to +125oC, input-referred noise less than 17.47 nV / Hz at 1kHz and active area of 0.117 mm2 in a 0.6 μm CMOS technology.