2026-09-19T09:26:16Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/166822022-01-13T07:54:29Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Kent H. Lundberg and Timothy A. Denison.
Paik, Song-Hee Cindy, 1980-
Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
2005-05-17T14:55:03Z
2005-05-17T14:55:03Z
2004
2004
http://hdl.handle.net/1721.1/16682
57138272
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.
Includes bibliographical references (p. 123).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Two main difficulties for amplifiers that attempt to make precision DC measurements are the inherent low-frequency noise of the amplifier and the leakage current of the amplifier input stage. This thesis presents a novel fully integrated operational amplifier design that addresses both measurement limitations by using a fully differential mechanical transductor input stage, fabricated using SOI-MEMS technology. The input stage of the amplifier is a MEMS structure that provides a variable capacitance to transduce a low-frequency input voltage into a high-frequency AC current. This up-modulation of the input signal is exploited to reduce offsets and low-frequency noise, and the dielectric isolation of the MEMS structure provides high input impedance and low leakage currents. To function, the MEMS-based amplifier includes two co-dependent feedback loops. The 'drive loop' utilizes closed-loop control to vibrate the MEMS structure at its mechanical resonant frequency to produce a modulating capacitance. The 'sense loop' senses the up-modulated signal from the MEMS structure, and provides gain and demodulation to this signal. Global feedback around the sense loop allows for accurate measurement of the input voltage.
by Song-Hee Cindy Paik.
M.Eng.
123 p.
937236 bytes
944283 bytes
application/pdf
application/pdf
eng
Massachusetts Institute of Technology
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http://dspace.mit.edu/handle/1721.1/7582
Electrical Engineering and Computer Science.
A MEMS-based precision operational amplifier
Microelectromechanical system-based precision operational amplifier
Thesis
application/pdf
Publication
unknown
unknown
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<Abstract>Two main difficulties for amplifiers that attempt to make precision DC measurements are the inherent low-frequency noise of the amplifier and the leakage current of the amplifier input stage. This thesis presents a novel fully integrated operational amplifier design that addresses both measurement limitations by using a fully differential mechanical transductor input stage, fabricated using SOI-MEMS technology. The input stage of the amplifier is a MEMS structure that provides a variable capacitance to transduce a low-frequency input voltage into a high-frequency AC current. This up-modulation of the input signal is exploited to reduce offsets and low-frequency noise, and the dielectric isolation of the MEMS structure provides high input impedance and low leakage currents. To function, the MEMS-based amplifier includes two co-dependent feedback loops. The 'drive loop' utilizes closed-loop control to vibrate the MEMS structure at its mechanical resonant frequency to produce a modulating capacitance. The 'sense loop' senses the up-modulated signal from the MEMS structure, and provides gain and demodulation to this signal. Global feedback around the sense loop allows for accurate measurement of the input voltage.</Abstract>
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