Fully Integrated Micromechanical Resonator Based Reference Oscillators
This project aims to achieve a fully integrated micromechanical based reference oscillator that meets or exceeds the requirements of the GSM standard. In addition to providing a highly accurate, on-chip frequency reference, a fully integrated oscillator can achieve greater stability (particularly acceleration sensitivity) and far less power consumption than any comparable off-chip oscillator. En route to achieving a fully integrated oscillator, much of the research is expected to focus on low-temperature metal processes that allow MEMS-last integration with MOS devices while retaining the stability and Q performance already offered by polysilicon counterparts.
Capacitive-Gap Micromechanical Local Oscillator at GHz Frequencies
This project aims to build a MEMS-based on-chip reference oscillator at GHz frequencies. By constructing an array of capacitive transduced micromechanical resonators with extremely small capacitive gaps and high mechanical Q, in conjunction with a low-power CMOS IC amplifier, it becomes possible to achieve self-sustained oscillation in a die-level system. While many applications for such high-frequency, low phase-noise oscillators exist, the initial goal is focused on creating a compact, low-power oscillator suitable for use in Rb atomic clock technologies. Combining with an atomic physics package, locking of the narrow linewidth oscillator to atomic transitions is possible by voltage-controlled frequency tuning via the electrostatic spring constant effect of the capacitive gaps.
A Micromechanical RF Channelizer for Cognitive Radio
Vibrating mechanical tank components, such as crystal and SAW resonators, are widely used for frequency selection in communication systems because of their high Q and exceptional stability. However, being off-chip components, these devices pose an important bottleneck against the ultimate miniaturization and performance of wireless transceivers. This project aims to explore the use of capacitively transduced micromechanical circuits to realize micromechanical mixer-filters with reconfigurable attributes. With their substantial size, cost and performance advantages, these devices can be used to realize a bank of tunable/switchable micromechanical filters for multi-band RF channel selection. By replacing all off-chip components with micromachined passive elements, micromechanical mixer-filters offer an alternative set of strategies for transceiver miniaturization and improvement. In the long term, this overall project aims to demonstrate an RF channelizer utilizing micromechanical elements in its signal path, exclusively, that presents one of the keys to eventually realizing a cognitive radio.