TY - GEN
T1 - A low-power low-noise capacitive sensing amplifier for integrated CMOS-MEMS inertial sensors
AU - Fang, Deyou
AU - Xie, Huikai
PY - 2004
Y1 - 2004
N2 - This paper presents a low-noise CMOS capacitive sensing amplifier with power consumption as low as 1mW for monolithic CMOS-MEMS inertial sensors. Low-power operation is achieved by using an open-loop, two-stage amplifier topology with fully differential input/output and chopper stabilization. High chopping frequency (up to 2 MHz) and capacitance matching with optimal transistor sizing are used to maximize signal-to-noise ratio. Offsets due to the sensor and circuits are reduced by ac offset calibration and dc offset cancellation. A pseudo-resistor MOS-Bipolar device is used to establish a stable dc bias at the sensing electrodes with very low noise. All the electronics, except the capacitor for the low-pass filter following the demodulation, are integrated on the same chip with MEMS inertial sensors. A prototype accelerometer integrated with this circuit has been fabricated using the TSMC 0.35-μm CMOS process with 3.3-V power supply. Experimental results show that this interface circuit achieves a gain of 40 dB over the chopper frequency range of 50 kHz to 1 MHz, with an equivalent input offset of about l mV. The sensor offset is attenuated by the interface circuit by more than 26 dB.
AB - This paper presents a low-noise CMOS capacitive sensing amplifier with power consumption as low as 1mW for monolithic CMOS-MEMS inertial sensors. Low-power operation is achieved by using an open-loop, two-stage amplifier topology with fully differential input/output and chopper stabilization. High chopping frequency (up to 2 MHz) and capacitance matching with optimal transistor sizing are used to maximize signal-to-noise ratio. Offsets due to the sensor and circuits are reduced by ac offset calibration and dc offset cancellation. A pseudo-resistor MOS-Bipolar device is used to establish a stable dc bias at the sensing electrodes with very low noise. All the electronics, except the capacitor for the low-pass filter following the demodulation, are integrated on the same chip with MEMS inertial sensors. A prototype accelerometer integrated with this circuit has been fabricated using the TSMC 0.35-μm CMOS process with 3.3-V power supply. Experimental results show that this interface circuit achieves a gain of 40 dB over the chopper frequency range of 50 kHz to 1 MHz, with an equivalent input offset of about l mV. The sensor offset is attenuated by the interface circuit by more than 26 dB.
KW - Capacitive interface circuits
KW - Chopper stabilization
KW - Integrated accelerometer
KW - Low power
KW - MEMS
KW - Preamplifier
UR - http://www.scopus.com/inward/record.url?scp=11144347180&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:11144347180
SN - 0889864551
SN - 9780889864559
T3 - Proceedings of the IASTED International Conference on Circuits, Signals, and Systems
SP - 96
EP - 101
BT - Proceedings of the IASTED International Conference on Circuits, Signals, and Systems
A2 - Rashid, M.H.
T2 - Proceedings of the IASTED International Conference on Circuits, Signals, and Systems
Y2 - 28 November 2004 through 1 December 2004
ER -