Flexible Film Bulk Acoustic Wave Filters toward Radiofrequency Wireless Communication. Issue 20 (30th March 2018)

• Record Type: Journal Article
• Authors: Jiang, Yuan; Zhao, Yuan; Zhang, Lin; Liu, Bohua; Li, Quanning; Zhang, Menglun; Pang, Wei
• Is Part Of: Small. Volume 14:Issue 20(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-03-30
• Subjects: film bulk acoustic wave resonator (FBAR) -- flexible electronics -- radiofrequency filters -- transfer printing; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201703644
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: This paper presents a flexible radiofrequency filter with a central frequency of 2.4 GHz based on film bulk acoustic wave resonators (FBARs). The flexible filter consists of five air‐gap type FBARs, each comprised of an aluminum nitride piezoelectric thin film sandwiched between two thin‐film electrodes. By transfer printing the inorganic film structure from a silicon wafer to an ultrathin polyimide substrate, high electrical performance and mechanical flexibility are achieved. The filter has a peak insertion loss of −1.14 dB, a 3 dB bandwidth of 107 MHz, and a temperature coefficient of frequency of −27 ppm °C −1 . The passband and roll‐off characteristics of the flexible filter are comparable with silicon‐based commercial products. No electrical performance degradation and mechanical failure occur under bending tests with a bending radius of 2.5 mm or after 100 bending cycles. The flexible FBAR filters are believed to be promising candidates for future flexible wireless communication systems. Abstract : A flexible radiofrequency filter based on film bulk acoustic wave resonators is fabricated on an ultrathin polyimide substrate. The filter shows a comparable performance with commercial silicon‐based filter and retains its high performance under a bending radius of 2.5 mm and 100 bending cycles.