Integrated multiple device CMOS-MEMS IMU systems and RF MEMS applications

This dissertation describes design, fabrication and test of multiple micro-electro-mechanical system (MEMS) inertial measurement unit (IMU) systems and RF MEMS applications. The multiple degree-of-freedom (DoF) sensing systems have advantages from integration, such as low cost and capabilities for cross device compensation. This work focuses on the CMOS-MEMS thin film lateral accelerometer and vertical gyroscope design and functional test. Structures fabricated by the post CMOS-MEMS surface micromaching process have mass smaller than 10−6 g. The mass displacement resulted from external acceleration is in the angstrom to nanometer range. Such small mass and displacement bring challenges to detect the extremely small signals, which are under 1mV/G and only a fraction of femtofarad change for the sensing capacitance. The sensing techniques and system integration issues are addressed. Non-idealities such as cross-axis coupling and acceleration interference are compensated with integration at the system level.; Applications using Q enhanced inductors by MEMS technology are also presented in this thesis. A voltage-controlled-oscillator (VCO) fabricated in a 0.18 μm copper CMOS process has a 2.2GHz oscillation frequency and phase noise of −60dBc/Hz at 100kHz offset. Another VCO fabricated in silicon-germanium (SiGe) BiCMOS process has a 5.1GHz oscillation frequency and phase noise of −73dBc/Hz at 100kHz offset.