Low-loss lateral-extensional piezoelectric filters on ultrananocrystalline diamond

Abstract

In this work, lateral-extensional thin-film piezoelectric- on-diamond (TPoD) filters with very low insertion loss (IL) values (<4 dB) are reported. Two different lateral-extensional modes of a resonant structure are coupled together to realize a two-pole filter. The filters of this work exhibit low IL values, with fractional bandwidth between 0.08% and 0.2%, and have a very small footprint. This paper reports on the lowest IL in the literature for lateral-extensional thin-film piezoelectric filters with 50 Ω terminations in the GSM frequency band (~900 MHz). The narrow-band filters of this work are fabricated on three ultrananocrystalline diamond substrates to achieve higher frequencies without excessive reduction in the feature size. The paper also thoroughly studies the parameters that affect the performance of such filters and then discussions are evaluated by the statistical data collected from the fabricated wafers.

Micromachined Resonators: A Review

“…Apart from realizing a piezoelectric resonator with only the piezoelectric film to define the structural layer, some research groups have implemented resonators comprising a thin piezoelectric film on a thick substrate layer. In this case, the structural layer is defined mainly by the substrate material, examples of which include single-crystal silicon [ 59 , 165 , 166 , 167 , 168 ], silicon carbide [ 169 , 170 , 171 ], and diamond [ 172 , 173 ].…”

A Battery-Less Wireless Respiratory Sensor Using Micro-Machined Thin-Film Piezoelectric Resonators

“…The MEMS used here, schematically shown in Figure 1, is composed of a piezoelectric layer sandwiched between two metal layers stacked on top of a nanocrystalline diamond substrate. AlN with a thickness of 500nm forms the piezoelectric layer and the nanocrystalline substrate has a thickness of 3µ m. Details of the operation of the MEMS device, including the design and fabrication process, can be found in [18,19].…”

“…AlN with a thickness of 500nm forms the piezoelectric layer and the nanocrystalline substrate has a thickness of 3 µm. Details of the operation of the MEMS device, including the design and fabrication process, can be found in [18,19].…”

“…Heat transferred from hot exhalatory flow to the resonator has the principal effect of lowering the effective stiffness of the resonator which in turn decreases the resonance frequency [19]. The temperature-frequency characteristic of an MEMS resonator is dependent on the properties of the material that constitutes the resonators.…”

High-frequency thin-film piezoelectric transformers

“…These resonators have been employed to build oscillators [1,2] and high performance filters [3,4]. One less-explored application for such resonators is impedance transformation that could be used in a transceiver architecture where impedance matching between high frequency components such as the front-end filter and the LNA is of interest.…”