Abstract
Sensitive capacitive transduction of micromechanical resonators can contribute significant electrical dissipation, which degrades the quality factor of the eigenmodes. We theoretically and experimentally demonstrate a scheme for isolating the electrical damping of a mechanical resonator due to Ohmic dissipation in the readout amplifier. The quality factor suppression arising from the amplifier is strongly dependent on the amplifier feedback resistance and parasitic capacitance. By studying the thermomechanical displacement noise spectrum of a doubly clamped micromechanical beam, we confirm that electrical dissipation tunes the actual, not effective, quality factor. Electrical dissipation is an important consideration in the design of sensitive capacitive displacement transducers, which are a key component in resonant sensors and oscillators.
Highlights
Increasing Q improves the thermomechanical signal-to-noise ratio (SNR) in resonant sensors and reduces the phase noise in oscillators
Electrical dissipation is an important consideration in the design of sensitive capacitive displacement transducers, which are a key component in resonant sensors and oscillators
The quality factor is traditionally limited by mechanical losses, such as anchor damping,[10,11,12] thermoelastic dissipation (TED),[13,14] the Akhiezer effect,[15,16,17] and surface losses,[18,19] and so a great deal of work has gone toward understanding and minimizing these sources
Summary
Increasing Q improves the thermomechanical signal-to-noise ratio (SNR) in resonant sensors and reduces the phase noise in oscillators.
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