Wireless, RF & Smart Dust

New resonator structural materials will be explored to achieve GHz-frequency MEMS resonators having ultra-high quality factors (Q's) and antenna-amenable motional impedances. Materials having acoustic velocities greater than that of polysilicon, such as diamond and silicon carbide (SiC), will be used to fabricate devices having higher resonance frequencies and higher Q's than their polysilicon counterparts. Low-loss metals, including metal alloys, will be investigated to achieve low deposition temperatures and high electrical conductivities while nonetheless maintaining high Q's....

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 ASIC amplifier, it becomes possible to achieve self-sustained oscillation in a die-level system. The high mechanical Q of these devices, which can reach an extraordinary >40,000 at frequencies up to 3GHz, allows the possibility for unprecedented phase noise performance. Many applications for such high-frequency, low phase-...

There has been recent interest in low noise mm-wave signals for satellite data communication and RADAR. For these applications, close in to the carrier phase-noise performance is important. Several competing very-low-phase-noise oscillator technologies exist at lower microwave frequencies. All of these face difficulties in being extended up to the new bands of interest. We propose using an optical frequency comb generator together with an optical interleaver to up convert the low noise, low frequency microwave signal to the desired high frequency bands without increasing the phase...

This project aims at developing high quality factor (Q), large coupling coeffecient (k2) aluminum nitride (AlN) Lamb wave resonators (LWRs) exhibiting low loss and thermally stable performance for wireless communications (e.g. oscillators or filters) in harsh environments. Current technology using thin AlN membrane structures have proved to enable a high phase velocity, low velocity dispersion of the Lamb wave employing the lowest order symmetric mode (S0), thus ensures a high frequency and offers robust designs with low sensitivity to technological tolerances. However, these devices...