Temperature compensated CMOS and MEMS-CMOS oscillators for clock generators and frequency references.

摘要

The purpose of this dissertation is to explore alternatives to quartz crystal based solutions to system clocking. While quartz has inherent advantages in terms of stability and cost, the inability to manufacture quartz in a standard silicon process impedes goals of miniaturization and system integration. A closer look at clocking requirements reveals widely different specifications for various applications. In addition to traditional CMOS oscillators such as ring and LC oscillators, the recent advent of micromachining technologies and MEMS resonators has provided a miniaturized, silicon alternative to quartz with potentially comparable performance levels. This provides the system designer with an option to make a clocking solution that most suits the system needs.;This work focuses on two aspects: the design of a stable CMOS ring oscillator for micro-controller type applications; and the design of electronics for an ultra-stable MEMS resonator based oscillator for reference oscillator applications. With the former approach, the focus of the research was the design of a process and temperature compensated oscillator to be stable to within 5%. The design, completed in a 0.25microm CMOS process, was stable to within 5.2% over 165°C and 4 different runs. With the MEMS oscillator, the aim of the research was to implement low phase noise, temperature stable oscillators over a wide frequency range. A novel temperature compensation technique was designed to reduce the temperature variation from 2800ppm to 39ppm over 100°C. The sources of phase noise in MEMS oscillators are analyzed and a 100MHz oscillator with sub-100ppm integrated jitter is demonstrated without the use of phase-locking techniques.