1/f noise in etched groove surface acoustic wave (SAW) resonators

Abstract

Measurements of 1/f (or flicker) frequency fluctuations in SAW resonators fabricated with etched groove reflectors on single crystal quartz have shown that the observed noise levels vary inversely with device size. These measurements were made on sixteen 450 MHz resonators of four different sizes. The 1/f noise levels were also evaluated on twenty-eight other SAW resonators ranging in frequency from 401 to 915 MHz. This additional data provides valuable information on the dependence of the flicker noise levels on resonator frequency. A model based an localized, independent velocity fluctuations in the quartz is proposed which correctly fits the observed size and frequency dependence of the measured 1/f noise levels. This model suggests that the velocity fluctuations originate in small regions (much less than ~5 mum in diameter) randomly distributed throughout the quartz with an average separation of about 5 mum between independent (incoherent) sources. The magnitude of the localized fractional velocity fluctuations, Deltav/v, averaged over a 5 micron cube is on the order of 1x10 (-9).

Quantum 1/f effect in resonant biochemical piezoelectric and MEMS sensors

“…For V < ε 3 , this is in agreement with the known data for quartz resonators of very high Q as experimental results obtained by Pikal and Walls [8], Parker et al [11] and Vig et al [12], as well as other research groups, indicate.…”

“…V is the quartz volume and C is a constant defined by (5) and (6). Here ε 3 is the phonon coherence volume, introduced empirically by Parker et al [10], [11] as a noise coherence volume. Usually, (5) is applicable to high stability BAW resonators, whereas (6) describes SAW resonators.…”

Phase Noise of SAW Delay Line Magnetic Field Sensors

“…Previous studies identified IDT metalizations [ 57 , 58 , 59 ] and the piezoelectric substrate [ 58 , 59 ] as the major sources of flicker noise in SAW devices. Mobile impurities or defects in the substrate cause fluctuations in the local acoustic wave velocity [ 59 ], thus leading to random phase fluctuations.…”

“…Mobile impurities or defects in the substrate cause fluctuations in the local acoustic wave velocity [ 59 ], thus leading to random phase fluctuations. In addition, due to a very strong sensitivity to surface conditions, the surface acoustic wave velocity is modulated by gas molecules adsorbed onto the surface [ 58 , 59 ]. For example, as early as 1979, it was reported that the flicker noise depends on the cleanliness of the surface [ 60 , 61 ].…”