Simultaneous mode tracking for sensing applications with dual-mode heterodyne NEMS oscillator
Abstract
We report the first experimental demonstration of a heterodyne self-oscillator operating simultaneously on the first
and second mode of a silicon NEMS resonator. This architecture tackles the simultaneous monitoring of a doubly-clamped
resonator’s first two resonant modes required for real world applications in the field of biological mass sensing. This oscillator
is based on a downmixing scheme where the NEMS motioninduced electrical signal around 25 MHz and 70 MHz is shifted
down to few tens of kilohertz thus reducing the bandwidth constraint on electronics and limiting the feedthrough between the
NEMS actuation and detection electrode. In this paper, we present the oscillator measurement results in open-loop and closed-loop, and we evaluate the frequency stability. When implemented on silicon this oscillator scheme will help to circumvent today’s
limited NEMS integration density mostly due to a bulky circuitry.
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