Title :
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
fDate :
2/1/1992 12:00:00 AM
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;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
