MEMS technology for timing and frequency control

Abstract

An overview on the use of microelectromechanical systems (MEMS) technologies for timing and frequency control is presented. In particular, micromechanical RF filters and reference oscillators based on recently demonstrated vibrating on-chip micromechanical resonators with Q's > 10,000 at 1.5 GHz are described as an attractive solution to the increasing count of RF components (e.g., filters) expected to be needed by future multiband, multimode wireless devices. With Q's this high in onchip abundance, such devices might also enable a paradigm shift in the design of timing and frequency control functions, where the advantages of high-Q are emphasized, rather than suppressed (e.g., due to size and cost reasons), resulting in enhanced robustness and power savings. Indeed, as vibrating RF MEMS devices are perceived more as circuit building blocks than as stand-alone devices, and as the frequency processing circuits they enable become larger and more complex, the makings of an integrated micromechanical circuit technology begin to take shape, perhaps with a functional breadth not unlike that of integrated transistor circuits. With even more aggressive three-dimensional MEMS technologies, even higher on-chip Q's are possible, such as already achieved via chip-scale atomic physics packages, which so far have achieved Q's > 10 7 using atomic cells measuring only 10 mm 3 in volume and consuming just 5 mW of power, all while still allowing atomic clock Allan deviations down to 10 ;11 at one hour.

Very High Frequency Silicon Nanowire Electromechanical Resonators

“…As illustrated by the f 0 × Q contours, our SiNWs have f 0 × Q in the 10 11 −10 12 Hz range, with SiNW-215 having f 0 × Q = 1.24 × 10 12 Hz. These products are comparable to those of the best top-down SiC UHF NEMS 24 and state-of-the-art MEMS beam resonators . Note that this is comparable to f 0 × Q' s recently reported for lower frequency, but higher Q , NEMS resonators under tension …”

“…These products are comparable to those of the best top-down SiC UHF NEMS 24 and state-of-the-art MEMS beam resonators. 25 Note that this is comparable to f 0 × Q's recently reported for lower frequency, but higher Q, NEMS resonators under tension. 26 As shown in Figure 4c, a clear correlation between the measured Q and device aspect ratio (length/width) is observed; larger aspect ratios yield higher Q's.…”

“…These will enable scaling fundamental resonance frequencies into the extreme UHF and low microwave range. Given their pW-to subpW operating power levels, SiNW resonators will enable future ultralow power applications such as high frequency mechanical signal processing, 25 mechanical logic applications, 6 and electromechanical qubits. 4 The suspended NEMS nanowire technology described herein, combined with the recent development of controlled epitaxial growth of selfaligned SiNW arrays, 31 should also now make it feasible to engineer SiNW-based resonator arrays to enable very-largescale nanomechanical device integration.…”

Optical wireless information transfer with nonlinear micromechanical resonators

“…Micro-and Nano-Electro-Mechanical Systems (MEMS and NEMS) resonators are of fundamental and technological interest, with applications ranging from timing in integrated circuits [1] to methods in quantum metrology [2,3], while operating in their linear regimes. At high drive amplitudes, these resonators exhibit nonlinear behavior, useful for studying fundamental effects such as stochastic resonance [4], parametric amplification and frequency entrainment [5], and logic operation [6].…”

Phase-locked loop based on nanoelectromechanical resonant-body field effect transistor

“…As basic building block for frequency clocks, 1 mixer-filters, 2 or super-abrupt switches, 3 NEMS are promising for future low power, mobile communication, and signal processing systems. 4 Nanomechanical resonators have emerged as a valuable tool to observe and prove quantum mechanics on macroscopic objects. 5 With shrinking device dimensions and increasing frequency of operation, NEMS are also exploited as sensors with unprecedented sensitivities.…”