High Overtone Bulk Resonator Stabilized Microwave Sources

Abstract

Several new techniques, d i e l e c t r i c resonators, SAW resonatcrs, skimming mode b u l k a c o u s t i c resonators and h i g h overtone b u l k a c o u s t i c wave (PAW) rescnators a r e k i n g advanced f o r low noise s t a b i l i z a t i o n of vicrowave s i g n a l sources.

High-Overtone Bulk Acoustic Resonator

“…The first approach consists in physical or chemical deposition of thin piezoelectric layers (such as ZnO, PZT, AlN and so on) onto the chosen substrate. The first HBAR was manufactured along this approach [11]. The main advantage of this kind of HBAR is the capability of the related techniques (sputtering, epitaxy, sol-gel spinning/firing, pulsed laser ablation, etc.)…”

“…Some works have already been done to compare and improve materials to favor high acoustic resonance quality [19], [11]. Figure 15 shows an example of these works [19].…”

“…The defect of parallelism between two surfaces of HBAR devices dramatically limits the quality factor [11]. Figure 16 shows the quality factor of HBAR modes on Sapphire-base structures versus the plate tilt.…”

Resonance Spectrum Characteristics of Effective Electromechanical Coupling Coefficient of High-Overtone Bulk Acoustic Resonator

“…The acoustic wave excited by the thickness vibration of an electrically loaded piezoelectric plate propagates into the substrate, which will lead to the standing wave resonance. Since the substrate thickness is much larger than the acoustic wavelength, the HBAR will operate at a number of resonance frequencies; namely, HBAR has multi-frequency resonance characteristics, and it can be used as a multiple-frequency microwave source [1] and an agile-frequency synthesizer in electronic warfare. Besides, HBAR has a large quality factor ( Q ) due to the low acoustic attenuation substrate, and exhibits the largest Q -Frequency product of the crystal oscillators.…”