A Micro-Watt Second Order Filter for a Chopper Stabilized MEMS Pressure Sensor Interface

Authors: Arup K. George, Wai Pan Chan, Zhi Hui Kong, Minkyu Je

Abstract:

This paper describes a low-power second-order filter for a continuous-time chopper stabilized capacitive sensor interface, integrated with a fully differential post-CMOS surface-micromachined MEMS pressure sensor. The circuit uses a single-ended folded-cascode operational amplifier and two GM-C filters connected in cascade. The circuit is realized in a 0.18 μm CMOS process and offers differential to single-ended conversion. The novelty of the scheme is the cascade of two GM-C filters to achieve a second-order filter while minimizing power dissipation. The simulated filter cutoff frequency is 1.14 kHz at common-mode voltage 1.65 V, operating from a 3.3 V supply while dissipating 172μW of power. The filter achieves an operating range of 1V for an output load of 1MOhm and 10pF.

Keywords: Chopper Stabilization, MEMS, Pressure Sensors, Low Pass Filter

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1334944

References:

[1] N. Ross and C. A. Eynon, "Intracranial pressure monitoring," Current Anaesthesia & Critical Care, vol. 16, pp. 255-261, 2005
[2] N. Yazdi, H. Kulah, and K. Najafi, "Precision readout circuits for capacitive micro-accelerometers," in Sensors, 2004. Proceedings of IEEE, 2004, pp. 28-31 vol.1.
[3] W. Jiangfeng, G. K. Fedder, and L. R. Carley, "A low-noise low-offset capacitive sensing amplifier for a 50╬╝g/ÔêÜHz monolithic CMOS MEMS accelerometer," IEEE Journal of Solid-State Circuits, vol. 39, pp. 722- 730, 2004.
[4] C.C. Enz, E.A.Vittoz, and F. Krummenacher, "A CMOS chopper amplifier," IEEE Journal of Solid-State Circuits, vol. 22, pp. 335-342, 1987.
[5] T. C. C. Kevin et.al, "118-dB dynamic range, continuous-time, openedloop capacitance to voltage converter readout for capacitive MEMS accelerometer," (A-SSCC) 2010, pp. 1-4.
[6] K. M. David A. Jones, "Analog Integrated Circuit Design," John Wiley and Sons