FBAR filters at GHz frequencies

Abstract

The Eilm Bulk Acoustic Resonator, or FBAR, is a new technology which has been used in the design and fabrication of microwave filters. These filters exhibit a combination of low loss, small size, frequency and bandwidth not attainable by any other type of device. Using a piezoelectric film of zinc oxide as a high Q crystal resonator along with passive components it is possible to form an integrable, high performance bandpass filter .The range of center frequencies achievable is roughly 1 to 5 GHz using current resonator designs. The technique features potentially low cost (since the filters are fabricated by batch processing), and, perhaps most intriguing, the capability of being combined with more complex functions (such as a complete radar receiver) as part of a larger mask set. Other advantages are moderate power handling capability, good temperature stability, and high dynamic range.

Validation of a Phase-Mass Characterization Concept and Interface for Acoustic Biosensors

“…A membrane FBAR is shown in Figure 1(b) . In the past few years, FBARs on silicon substrates have been taken into account for filter applications in RF devices [ 20 ]. Gabl et al .…”

Development of <inline-formula><math display="inline" overflow="scroll"><mrow><mn>2.4</mn><mtext>-</mtext><mi>GHz</mi></mrow></math></inline-formula> film bulk acoustic wave filter for wireless communication

“…1 In the 1990s, the gigahertz FBAR was presented. 2 In this paper, the FBARs connecting some inductors and capacitors are used for the gigahertz filter application. Also in the 1990s, FBARs were integrated with a heterojunction-bipolar-transistor amplifier on a GaAs substrate.…”

Thin film resonator technology

“…Using microelectronics processing techniques it was possible to fabricate thin membrane structures on silicon substrates using a wafer-scale manufacturing process that resulted in composite but nevertheless fundamental mode resonators with high effective coupling coefficients necessary for filter synthesis [20][21][22][23][24][25][26].…”

“…Electrically connected resonators form ladder, lattice, or other similar circuits. Ladder filters are made with resonators having different frequencies as required to synthesize the passband response [36][37][38][39][40][41]. The simplest filter has all the series resonators at the same frequency and the shunt resonators at a lower frequency so that the parallel resonance of the shunt resonator is at approximately the series resonant frequency of the series resonators.…”