CMOS chopper amplifier for chemical sensor

Author

Wei, Sen-Jung ; Lin, Hung Chang

Author_Institution

Dept. of Electr. Eng., Maryland Univ., College Park, MD, USA

Volume

41

Issue

1

fYear

1992

fDate

2/1/1992 12:00:00 AM

Firstpage

77

Lastpage

80

Abstract

A highly sensitive CMOS chopper amplifier for an oxygen probe is described. It is integrated in a 2-μm double-poly p-well CMOS process. The chip uses only a single 5-V voltage source, and no external components are needed. It is realized by using the current mode chopper technique to overcome the low frequency noise and drift problems. The clock feedthrough generated by the chopper circuit is reduced by using the switched-capacitor-filter technique. The switched-capacitor technique is also used to implement the function of demodulation. The simulated current is converted into an output voltage with a slope of approximately 100 mV/nA. The current signal from 0.2 to 8 nA can be measured with a nonlinearity of 3.5%. Experimental results are given showing the performance of this amplifier

Keywords

CMOS integrated circuits; choppers (circuits); electric sensing devices; gas sensors; instrumentation amplifiers; linear integrated circuits; operational amplifiers; oxygen; switched capacitor networks; 0.2 to 8 nA; 2 micron; 5 V; CMOS chopper amplifier; DC current; O₂ probe; blood; chemical sensor; clock feedthrough; current mode chopper; demodulation; double-poly p-well CMOS process; drift; noise; switched-capacitor-filter; CMOS process; Chemical sensors; Choppers; Circuit simulation; Clocks; Demodulation; Low-frequency noise; Probes; Switching circuits; Voltage;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.126636

Filename

126636