High performance amplifier topologies implemented with a micro-machined vibrating capacitor

In this work, the design of a MEMS based differential amplifier is investigated. The goal of this investigation is to design, fabricate and characterize a differential amplifier whose performance is based on a physically coupled, but electrically isolated fully differential mechanical transconductor input stage that is fabricated using SOI-MEMS technology. The MEMS sensor will act as a vibrating capacitor input stage. It will provide galvanic isolation and up-modulation of the input signal as it vibrates. The galvanic isolation facilitates low-leakage inputs and a very wide input common mode voltage range. The up-modulation provides a means for achieving a low input referred offset voltage and low-noise via the use of correlated double sampling or chopper stabilization. At the system level, this amplifier consists of two major loops: the drive loop and a sense loop. The drive loop includes half of the MEMS structure along with some electronics and provides a means of moving the beam at a constant frequency. The drive loop's design was facilitated by describing function analysis. The drive loop vibrated the beam at its mechanical resonance because at that frequency, the displacement of the beam is maximized for a given electrostatic force and consequently, the sensitivity of the amplifier is maximized. The sense loop includes the other half of the beam and some electronics whose role is to process the differential input signal applied at the MEMS structure's inputs. Common-mode rejection is performed by the mechanical transconductor, while the sense loop's crossover frequency sets the signal bandwidth.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Aina, Akin Adeniyi, 1974-

Advisor dc:contributor.advisor

• Timothy Denison and Steven Leeb.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/17595

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/17595