Intrinsically Switchable and Bandwidth Reconfigurable Ferroelectric Bulk Acoustic Wave Filters

Koohi, Milad Zolfagharloo; Nam, Suhyun; Mortazawi, Amir

doi:10.1109/tuffc.2019.2958675

Cited by 21 publications

(6 citation statements)

References 16 publications

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“…Circuit schematic of the six-stage six-pole/twelve-TZ BPF alongside with its ideally-simulated S-parameters. [13], [22] only allow for reconfigurable transfer function states and the BPF in [12] facilitates discrete BW tuning. Lastly, the AWLR BPF concept in [19] is based on mechanically-tunable capacitors.…”

Section: Experimental Validationmentioning

confidence: 99%

“…However, most of them facilitate discrete RF tuning. For example, in [12], [13], a ferroelectric material is used within a thin-film bulk acoustic resonator (FBAR) resonator to turn its resonance ON or OFF in the presence or absence of DC biasing. This concept has been exploited for the realization of intrinsically-switchable filter banks and RF filters with tunable FBW, however it relies on a fairly complicated manufacturing process and is only suitable for discrete tuning.…”

Section: Introductionmentioning

confidence: 99%

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Acoustic Wave Resonator-Based Bandpass Filters With Continuously Tunable Fractional Bandwidth

Nasser

Psychogiou

2023

IEEE Trans. Circuits Syst. II

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A new class of acoustic-wave resonator-based bandpass filters (BPFs) with continuously tunable fractional bandwidth (FBW) are presented. They are based on cascaded multi-resonant stages of hybridly-integrated surface acoustic wave (SAW) resonators with lumped element (LE) components. Each stage comprises one SAW resonator and one or more LE resonators that contribute to the overall transfer function to one pole and two transmission zeros (TZs). As such highly-selective quasi-elliptic transfer functions with N poles, 2N TZs and enhanced FBW can be created for two series and N-2 parallel stages. It is shown that by reconfiguring the resonant frequency of the LE resonators, continuously-tunable FBWs can be obtained. The operating principles of the multi-stage concept are demonstrated through design examples of multi-stage prototypes. The concept has been validated at 916.6 MHz through a fourpole/eight-TZ BPF with tunable BW between 0.63-1.32 MHz (i.e., FBW=0.57 -1.32kt 2 ), minimum in-band insertion loss (IL) 3.9-2.3 dB (Qeff =7700-6000) and out-of-band isolation > 27 dB. Index Terms-Acoustic wave resonator (AWR), high quality factor (Q), tunable bandpass filter (BPF), kt 2 -enhancement.

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Section: Experimental Validationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Acoustic Wave Resonator-Based Bandpass Filters With Continuously Tunable Fractional Bandwidth

Nasser

Psychogiou

2023

IEEE Trans. Circuits Syst. II

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“…Over the past years, tunable bandpass filters (BPFs) have drawn a lot of attentions in the modern microwave device due to its potential for miniaturization, complexity and cost reduction. The technologies for tunable BPFs can be summarized as follows: micro-electro mechanical system [1], yttrium iron garnet [2,3], ferroelectric [4,5], liquid metal [6,7] and varactor diode [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Among these, varactor-loaded tunable BPF has the advantages of fast tuning speed, compact size, low cost and low weight.…”

Section: Introductionmentioning

confidence: 99%

A tunable bandpass filter with extended passband bandwitdh

Dong

Yang

2022

Int. J. Microw. Wireless Technol.

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An Nth-order tunable bandpass filter (BPF) structure with extended passband bandwidth has been proposed in this paper based on the novel tunable resonator and coupling structure. The designed tunable resonator is composed of two coupled lines and one varactor diode, while the presented tunable coupling structure is constructed by two cascaded transmission lines and one short-circuited varactor diode. Moreover, the even-(odd-) method and lumped-element equivalent circuit are employed to analyze the operating mechanisms of the designed Nth-order tunable BPF. Specifically, the frequency tuning range is determined by the characteristic impedance and electrical length of coupled line when the varactor diode is within the fixed tuning range. Then, the design procedure for the Nth-order tunable BPFs is proposed. To demonstrate the presented idea, the second- and third-order fully tunable BPFs have been designed and simulated. Finally, a second-order tunable BPF with the compact size of 0.03λg × 0.13λg has been fabricated and measured, and the measured center frequencies are ranging from 0.91 to 1.46 GHz with the passband bandwidths wider than 11.2%.

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“…[8] However, most of the acoustic devices based on PZT and BST have several limitations, including limited Q factor, a lack of complementary metal-oxide-semiconductor (CMOS)-compatible fabrication processes, and a DC bias requirement to turn on the device in the case of BST. [9][10][11] Recently, ferroelectric properties have been discovered in thin-film aluminum scandium nitride (Al 1Àx Sc x N) with x > 27%. [12] Due to the infancy of the field, a fundamental study of various mechanisms that are a result of polarization switching in ferroelectric-doped AlN films has not been conducted to date.…”

Section: Introductionmentioning

confidence: 99%

Ferroelectric Aluminum Scandium Nitride Thin Film Bulk Acoustic Resonators with Polarization‐Dependent Operating States

Wang

Zheng

Ansari

2021

Physica Rapid Research Ltrs

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Given the recent discovery of ferroelectricity in highly doped AlN films and their widespread use in bulk acoustic wave (BAW) filters, the ferroelectric and acoustic performance of AlScN‐based devices at two distinct polarization states, i.e., nitrogen (N)‐polar and metal‐polar states, is investigated. Unreleased metal−ferroelectric−metal (MFM) capacitors, as well as suspended MFM structures in the form of thin‐film bulk acoustic resonators (FBARs), are fabricated based on Mo/AlScN/Mo‐sputtered films with ≈30% Sc concentration. The hysteresis polarization−electric field (P−E) loops and internal resistance of the MFM capacitors are characterized. The FBAR devices are characterized at the two polarization states, where the polarization inversion is accompanied by the modulation of thin‐film stress and resistance. Furthermore, the as‐fabricated N‐polar FBAR shows a fundamental thickness‐mode resonance frequency of 3.17 GHz, with a quality factor (QBode) of 572 and a high effective electromechanical coupling coefficient (kt2) of 11.4%. The FBAR frequency response changes when the polarization is switched from N‐polar to metal‐polar. Herein, the first investigations of electric and acoustic properties of N‐polar and metal‐polar AlScN‐based devices are demonstrated, paving the way for the realization of high‐kt2‐reconfigurable acoustic filters for next‐generation communication systems operating at the super‐high‐frequency (SHF) range.

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Intrinsically Switchable and Bandwidth Reconfigurable Ferroelectric Bulk Acoustic Wave Filters

Cited by 21 publications

References 16 publications

Acoustic Wave Resonator-Based Bandpass Filters With Continuously Tunable Fractional Bandwidth

Acoustic Wave Resonator-Based Bandpass Filters With Continuously Tunable Fractional Bandwidth

A tunable bandpass filter with extended passband bandwitdh

Ferroelectric Aluminum Scandium Nitride Thin Film Bulk Acoustic Resonators with Polarization‐Dependent Operating States

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