Title :
A fully integrated, untrimmed CMOS instrumentation amplifier with submicrovolt offset
Author :
Menolfi, Christian ; Huang, Qiuting
Author_Institution :
Integrated Syst. Lab., Fed. Inst. of Technol., Zurich, Switzerland
fDate :
3/1/1999 12:00:00 AM
Abstract :
A low-noise CMOS instrumentation amplifier intended for low-frequency thermoelectric microsensor applications is presented that achieves submicrovolt offset and noise. Key to its performance is the chopper modulation technique combined with a bandpass filter and a matching on-chip oscillator. No external components or trimming are required. The achievable offset performance depends on the bandpass filter Q and the oscillator-to-bandpass filter matching accuracy. Constraints are derived for an optimum Q and a given matching accuracy. The improvement of common-mode rejection ratio (CMRR) in chopper amplifiers is discussed. The amplifier features a total gain of 77±0.3 dB and a bandwidth of approximately 600 Hz. The measured low-frequency input noise is 8.5 nV/√Hz and the input offset is 600 nV. The measured low-frequency CMRR is better than 150 dB. The circuit has been implemented in a standard 1-μm single-poly CMOS process
Keywords :
CMOS analogue integrated circuits; impedance matching; instrumentation amplifiers; microsensors; 1 micron; 600 Hz; 600 nV; 76.7 to 77.3 dB; bandpass filter; bandwidth; chopper modulation technique; common-mode rejection ratio; low-frequency CMRR; low-frequency thermoelectric microsensor; oscillator-to-bandpass filter matching accuracy; single-poly CMOS process; submicrovolt offset; total gain; untrimmed CMOS instrumentation amplifier; Band pass filters; Choppers; Gain; Instruments; Low-frequency noise; Low-noise amplifiers; Matched filters; Microsensors; Oscillators; Thermoelectricity;
Journal_Title :
Solid-State Circuits, IEEE Journal of
