936 research outputs found
A Nanoscale Parametric Feedback Oscillator
We describe and demonstrate a new oscillator topology, the parametric feedback oscillator (PFO). The PFO paradigm is applicable to a wide variety of nanoscale devices and opens the possibility of new classes of oscillators employing innovative frequency-determining elements, such as nanoelectromechanical systems (NEMS), facilitating integration with circuitry and system-size reduction. We show that the PFO topology can also improve nanoscale oscillator performance by circumventing detrimental effects that are otherwise imposed by the strong device nonlinearity in this size regime
A Comparative Study Between a Micromechanical Cantilever Resonator and MEMS-based Passives for Band-pass Filtering Application
Over the past few years, significant growth has been observed in using MEMS
based passive components in the RF microelectronics domain, especially in
transceiver components. This is due to some excellent properties of the MEMS
devices like low loss, excellent isolation etc. in the microwave frequency
domain where the on-chip passives normally tend to become leakier and degrades
the transceiver performance. This paper presents a comparative analysis between
MEMS-resonator based and MEMS-passives based band-pass filter configurations
for RF applications, along with their design, simulation, fabrication and
characterization. The filters were designed to have a center frequency of 455
kHz, meant for use as the intermediate frequency (IF) filter in superheterodyne
receivers. The filter structures have been fabricated in PolyMUMPs process, a
three-polysilicon layer surface micromachining process.Comment: 6 pages, 15 figure
Reconstruction of annular bi-layered media in cylindrical waveguide section
A radial transverse resonance model for two cylindrical concentric layers
with different complex dielectric constants is presented. An inverse problem
with four unknowns - 3 physical material parameters and one dimensional
dielectric layer thickness parameter- is solved by employing TE110 and TE210
modes with different radial field distribution. First a Newton-Raphson
algorithm is used to solve a least square problem with a Lorentzian function
(as resonance model and "measured" data generator). Then found resonance
frequencies and quality factors are used in a second inverse Newton-Raphson
algorithm that solves four transverse resonance equations in order to get four
unknown parameters. The use of TE110 and TE210 models offers one dimensional
radial tomographic capability. An open ended coax quarter-wave resonator is
added to the sensor topology, and the effect on the convergence is
investigated
Buckled Diamond-like Carbon Nanomechanical Resonators
We have developed capacitively-transduced nanomechanical resonators using
sp-rich diamond-like carbon (DLC) thin films as conducting membranes. The
electrically conducting DLC films were grown by physical vapor deposition at a
temperature of C. Characterizing the resonant response, we
find a larger than expected frequency tuning that we attribute to the membrane
being buckled upwards, away from the bottom electrode. The possibility of using
buckled resonators to increase frequency tuning can be of advantage in rf
applications such as tunable GHz filters and voltage-controlled oscillators.Comment: 5 + 4 pages, 3 + 4 figure
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