Film Bulk Acoustic Resonator Technology Research Articles

Design of Hybrid Bandpass Filter Chips with High Selectivity and Wideband Using IPD and FBAR Technology

A novel hybrid bandpass filter (BPF) with wideband and high selectivity is proposed in this paper. The hybrid BPF is composed of two film bulk acoustic resonator (FBAR) cells and three lumped component resonators realized by the integrated passive device (IPD) technology. The ABCD matrix to S-parameters matrix method is used to calculate the frequency response of the BPF. Moreover, the expressions of transmission zeros (TZs) have been extracted. In the design process, an iterative design approach is proposed to improve the circuit and layout of the hybrid filter based on the packaged acoustic-electric hybrid simulation effect. Finally, two parts of the filter are packaged based on the flip-chip method, and two prototypes for the BPF are measured. The measured results of two chips with 3 dB fractional bandwidth of 13.7% and 15.8% are designed and fabricated, which verifies the validity of the proposed design principle.

A 3.4–3.6 GHz High-Selectivity Filter Chip Based on Film Bulk Acoustic Resonator Technology

The development of mobile 5G technology poses new challenges for high-frequency and high-performance filters. However, current commercial acoustic wave filters mainly focus on 4G LTE, which operates below 3 GHz. It is necessary to accelerate research on high-frequency acoustic wave filters. A high-selectivity film bulk acoustic resonator (FBAR) filter chip for the 3.4–3.6 GHz range was designed and fabricated in this paper. The design procedure includes FBAR parameter fitting, filter schematic analysis, and the generation principle of transmission zeros (TZs). The measured results show that the filter chip is of high roll-off and stopband suppression. Most of the stopband suppression is better than 35 dB. Finally, error analysis was conducted, and FBAR parameters were modified after testing for future filter design work.

Two-dimensional analysis of FBAR by using FDTD method

The film bulk acoustic resonator (FBAR) devices are lighter, smaller, cheaper and capable of dealing with larger power than SAW devices. Therefore, the FBAR technology is more competitive in satisfying the commands of modern mobile phone systems. In this paper, the finite-difference time-domain method is applied to analyze the two-dimensional thin-film bulk acoustic wave resonators. The piezoelectric governing equations and Newton's equation of motion are discretized to centered finite-differences in spatial and temporal domain. An electrostatic field simulator named ANSOFT Maxwell 2D is used to calculate the electric field intensity. The frequency domain electrical impedance characteristics of FBAR with different electrode thicknesses are calculated by using the Prony's method. From the simulation results, the optimal electrode thickness is suggested.

Positioning FBAR technology in the frequency and timing domain

This paper focuses on the technical differentiation of film bulk acoustic resonator (FBAR) technology from other mechanical resonator technologies for timing applications. The paper will touch on a recent modification of FBARs, the zero-drift resonator (ZDR), that is temperature compensated. One technology differentiator is the size of the chip-scale packaged resonator. Another is that the silicon lid is perfectly suitable for placement of integrated circuits and this is currently being done. Many factors (wide tuning range, high Q, high frequency, small size, integrated circuitry) are being used to differentiate potential products for the time and frequency markets.

Recent developments in thin film electro-acoustic technology for biosensor applications

The article reviews recent developments of the thin film electro-acoustic (TEA) technology in view of the design and fabrication of micro-acoustic transducers for biosensor applications. The use of the TEA technology leads to transducer miniaturisation, compatibility with the IC technology, possibility for multiplexing, decrease in fabrication cost, reduction of consumables, mass fabrication, etc. Focus lies on the design, fabrication and evaluation of the transducer performance in liquid media as judged by electro-acoustic behaviour and ultimately by mass and viscosity resolution. The analysis draws the conclusion that the thickness excited quasi-shear thin film bulk acoustic resonator technology is far ahead in its development with regard to other alternative approaches in terms of both performance and level of maturity. Consequently, the main aspects of the quasi-shear thin film bulk acoustic resonator (FBAR) technology from film synthesis and fabrication through to performance evaluation and demonstration are reviewed in detail.

Monolithic 1-Chip FBAR duplexer for W-CDMA handsets

Film bulk acoustic resonator (FBAR) filters and duplexers are receiving increasing attentions in RF systems due to the advantages of having high power handling capability, high Q-factors, good thermal stability, require a small volume and are relatively cheap. There are currently no published papers and research about FBAR 1-Chip duplexer, which have been designed with Tx and Rx filters because it is a very challenging task. We report for the first time that a monolithic 1-Chip RF duplexer is achieved with the size of 2.5 mm × 2.5 mm using thin FBAR technology to meet the stringent demand for miniaturization and monolithic integration of duplexers in RF communication systems. In this work, a novel 1-Chip duplexer is designed by EM (electromagnetic) simulation and RF circuit simulation using HFSS and ADS. The highest insertion losses in the pass band (1920–1980, 2110–2170 MHz) are measured below 4.35 dB, and attenuation are over 39 dB.