system and circuit design for a capacitive mems gyroscope - Aaltodoc
system and circuit design for a capacitive mems gyroscope - Aaltodoc
system and circuit design for a capacitive mems gyroscope - Aaltodoc
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1.4 Organization of the Thesis 7<br />
resonator control loops are studied. The possibility of using ΣΔ modulation to extend<br />
the resolution is introduced.<br />
In Chapter 5, issues related to the compensation of the mechanical quadrature sig-<br />
nal are studied. First, various compensation methods are introduced. Different ways<br />
to implement the control loop <strong>for</strong> the compensation are presented, concentrating on<br />
a case where the compensation voltage is generated with a DAC <strong>and</strong> the controller is<br />
digital. In particular, extending the resolution with ΣΔ techniques is studied.<br />
In Chapter 6, one of the most significant non-idealities of an angular velocity sen-<br />
sor, the ZRO, is studied. Different sources <strong>for</strong> the ZRO are discussed, <strong>and</strong> they are<br />
given a uni<strong>for</strong>m mathematical representation. Ways to minimize the effect of these<br />
sources on the final ZRO are considered. How electrostatic quadrature compensation<br />
per<strong>for</strong>med with a dc voltage affects the ZRO is also analyzed.<br />
Chapters 7-8 concentrate on the electronics <strong>design</strong> <strong>and</strong> the <strong>system</strong> that was imple-<br />
mented. In Chapter 7, several possible ways to per<strong>for</strong>m the readout of a <strong>capacitive</strong><br />
sensor are studied. These include both continuous-time <strong>and</strong> discrete-time implemen-<br />
tations. Additionally, the interaction between the readout <strong>circuit</strong> <strong>and</strong> the mechanical<br />
element through electrostatic <strong>for</strong>ces is discussed.<br />
In Chapter 8, the implemented MEMS angular velocity sensor is presented. The<br />
<strong>system</strong> <strong>design</strong> <strong>and</strong> the <strong>design</strong> of the sensor readout electronics are introduced in detail.<br />
The other analog <strong>circuit</strong> blocks <strong>and</strong> the required DSP are discussed on a more general<br />
level. The measurement results achieved with the implemented <strong>system</strong> are presented.<br />
Finally, the thesis is concluded in Chapter 9.
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