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Bulk acoustic waves excited in thin piezoelectric films have revealed their capabilities for addressing the problem of high frequency RF filters and frequency sources (above 1 GHz). In this paper, we propose an alternative to thin film deposition consisting in single crystal wafers bonded on substrate (high quality) and thinned down, allowing for plate thickness close to 30 mum. This has been achieved...
We used a high quality AlN film deposited by sputtering onto a thin silicon device layer (30 mum thick) to fabricate a 2.4 GHz oscillator and to improve the spectral separation. The substrate consists in a 4" thick silicon on insulator (SOI) wafer. The aluminium nitride was deposited by pulsed direct current reactive sputtering onto a platinum electrode. BAW resonators were formed together with...
Harmonic bulk acoustic resonators are build on a SOI to allow for a good spectral separation of the device resonance. SOI is etched back to allow for the fabrication of well defined resonance in the vicinity of 2.45 GHz. Thermal sensitivity close to -25 ppm/K also was measured. The analysis of experimental data obtained for resonance taking place in the whole stack allows for emphasizing a dispersive...
This paper reports on the design and the measurement of low phase noise X-band oscillators combining a room temperature high-Q whispering gallery mode (WGM) sapphire resonator and an ultra-low phase noise sustaining amplifier. The resonator thermal configuration has been optimized leading to a thermal frequency sensitivity of -0.05 ppm/K. Compact microstrip DBR (dual behavior resonators) filters have...
A growing number of scientific or technical applications requires very high frequency stability oscillators. Thus a frequency stability of the order of 1×10−14 at short term is now required for metrology, future space programs and some tests of fundamental physics. Besides any reduction in oscillators phase noise will improve radar systems and phase noise measurement sensitivity. These new requirements...
The flicker noise of the ferrite circulator is a critical element in ultra-stable microwave oscillators, in which the signal reflected from the input of the reference cavity is exploited to stabilize the frequency. This paper explains why the circulator noise must be measured in isolation mode, proposes a measurement scheme, and provides experimental results. The observed flicker spans from -162 to...
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