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Tesi etd-04012008-190557


Thesis type
Tesi di dottorato di ricerca
Author
NIZZA, NICOLO'
email address
nicolo.nizza@gmail.com
URN
etd-04012008-190557
Title
CMOS INTEGRATED CIRCUITS FOR CAPACITIVE SENSORS INTERFACING
Settore scientifico disciplinare
ING-INF/01
Corso di studi
INGEGNERIA DELL'INFORMAZIONE
Commissione
Relatore Prof. Nannini, Andrea
Relatore Prof. Bruschi, Paolo
Parole chiave
  • analog-mixed signal IC design
  • analog CMOS design
  • MEMS interfaces design
Data inizio appello
09/06/2008;
Consultabilità
parziale
Data di rilascio
09/06/2048
Riassunto analitico
Since large scientific and economic interests reside in micro-electromechanical systems (MEMS), this thesis has been focused mainly on the design of read-out channels for capacitive integrated sensors. In the first Chapter an introduction on micro-electromechanical systems and their applications are presented. The mechanical structure of capacitive MEMS, their different transduction interfaces and their future applications in wireless sensor network are illustrated. <br>In the second Chapter, an interface for a capacitive pressure sensor is described. First the details of the capacitance to voltage conversion interface are shown; then two different techniques used to correct the linearity error related to the sensor characteristic are explained. The first approach uses a non-linear analog amplifier, the second method uses an analog to digital converter with a non linear characteristic. <br>In the third Chapter, an interface that converts capacitance variations produced by a capacitive pressure sensor in an output pulse width modulated (PWM) signal is shown. A detailed analysis of different contributions due to non-idealities sources of the circuit is discussed; a comparison between the theoretical prediction and experimental measurements on a test chip are shown.<br>In the fourth Chapter, a second version of circuit presented in the third chapter is shown; the circuit have a reduced power consumption and a better immunity to disturbs. The working principle is described in details, a theoretical analysis underlines possible causes of non ideality identifying the strategies which allow to reduce the effect of these disturbances. <br>In the fifth Chapter, the implementation of a sigma-delta analog to digital converter (SD-ADC) using the 45 nm CMOS process and with a sampling frequency of 1 GHz is presented. The design flow of two different SD-ADC is discussed; the two converters have respectively a feedback and a feedforward architecture. <br>Finally in the sixth Chapter, a technique that allows to transform an operational transconductive amplifier (OTA) from class A to class-AB is presented. The advantages of the proposed method respect other techniques present in literature are shown, also some other improvements that is possible to get respect the original cell are discussed. <br>
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