978-1-7281-1536-8/18/$31.00 ©2018 IEEE 237 FILM BULK ACOUSTIC WAVE RESONATOR IN RF FILTERS MUHAMMAD HUNAIN MEMON 1 , ZAKIR KHAN 1 , MUHAMMAD HAMMAD MEMON 2 , SHUO CHEN 1 , FUJIANG LIN 1 1 Micro-/Nano Electronic System Integration R&D center (MESIC), Department of Electronic Science and Technology, University of Science and Technology of China, Hefei, China. 2 School of Computer Science and Engineering University of Electronic Science and Technology of china, Chengdu E-MAIL: hunainmemon@ieee.org, zakirkhan@mail.ustc.edu.cn, muahmmadhammadmemon@yahoo.com csbao@mail.ustc.edu.cn, fujiang_lin@ieee.org Abstract: Film Bulk Acoustic Resonator (FBAR) is widely used as a RF filter in advanced wireless communication system because of its high-Quality Factor (Q) and low in- band losses. FBAR is also widely used as a sensor for biomedical and physical sensing. This paper describes the basic concepts of FBAR, device architecture, and the topology used to design the filter. Furthermore, we have proposed the design of 3D-FBAR based on cavity device architecture which can be used to design a RF-filter. In this design, aluminum (Al) is used as a top as well as for the bottom electrode the top electrode is hexahedron in shape, aluminum nitride (AlN) as a piezoelectric and silicon (Si) is used as a substrate. The designed model is to analyses maximum pressure of FBAR in its operating region, the resonant frequency fr which is 2.76 GHz and anti-resonant frequency fa which is 2.78 GHz and Q- factor is 730. Keywords: RF-MEMS; FBAR; RF Filters; Acoustic wave 1. Introduction In wireless communication systems, such as cellphone communication system, satellite communication system and other communication systems, filtering process is one of the highlighted issues when the operating frequency is up to medium or high GHz range. The development of high performance, small size, resonators and filter on chip operating in GHz frequency range is the requirement of present and future wireless communication systems. The radio frequency (RF) filters have different types in which the operating frequency range is from 100 MHz to 10 GHz. The RF filters of high frequency in GHz comes under the category of microwave filters [1-3]. Film bulk acoustic wave resonators (FBARs) based RF filters is on high demand in the current wireless communication systems as well as upcoming wireless communication systems [4]. The evolution of smartphones with their ongoing generation of network, e.g. 3G, 4G/LTE and other wireless access methods, e.g. WIFI, Bluetooth, GPS receiver path have increased the need of advanced filter technology. Radio-frequency (RF) filters in communication systems based on FBAR technology have attracted major interests to be fabricated. This is because of their admirable features that are high Q, miniature and CMOS compatibility [5]. Power consumption remains the most highlighted factor in wireless communication systems and low power consumption designs in modern wireless communication system are in need [6]. Heavy weighted batteries and devices are not preferred from the consumers side. So, the key design goal is to achieve the lowest power consumption. Thus, low loss and high-quality factor (Q) for filter elements are absolute requirements in wireless system design. Most common application of FBARs is radio frequency (RF) filters which are used in telecommunication systems. Filters made from a resonator network are designed to suppress out-of-band frequencies from being transmitted or received through the communication system on the other hand, the desired frequencies are transmitted or received with a very low in band losses. Acoustic waves are generated when the piezoelectric material is excited by an electrical field. piezoelectric material converts that electrical energy into mechanical energy when an electrical energy is applied and vice versa. FBAR uses film of piezoelectric material with electrodes on the both sides and supporting layer or bragg acoustic reflector. Piezoelectric thin film generates a bulk acoustic wave inside when it is sandwiched between the electrodes, when the high frequency signal is applied to the electrodes. The thin film thickness of the piezo-electric material controls the resonating wave frequency. A resonator with such a structure is called a film bulk acoustic resonator (FBAR).