Integration of a CMOS Preamplifier with a Lead Zirconate Titanate Resonant Frequency Microsensor

We report in this paper on the fabrication of a two-stage, folded-cascode complementary metal oxide semiconductor (CMOS) amplifier and a resonant frequency microsensor. The fabrication of a CMOS amplifier was performed in the microtechnology laboratory at the University of Minnesota for applications in microelectromechanical (MEM)-based sensors. The fabrication of a CMOS amplifier employs the University of Minnesota 3 μm CMOS process. Results from circuit measurements show the 3 dB frequency of 600 kHz, the unity-gain frequency of 3.78 MHz, and the dc gain of 14 dB. The phase margin is around 83°. For the fabrication of a resonant frequency microsensor, Pb(Zr 0.53 Ti 0.47 )O 3 (lead zirconate titanate, PZT) thin film was used. PZT is a promising piezoelectric material for fabricating MEMs-based sensors and actuators on a silicon substrate. The resonant frequency microsensor reaches a maximum in amplitude at 133 kHz. The sensor was connected to the fabricated CMOS amplifier. Then a 10 mV p-p sine wave of 1.5 MHz was driven to the sensor. The output of 5 mV p-p at 1.5 MHz was obtained from the output of the CMOS amplifier.