Improved coupled resonator filter performance using a carbon-doped oxide de-coupling layer

Gilbert, Stephen R.; Nikkel, P.; Jamneala, T.; Ruby, R.; Larson, J.D.; Thalhammer, Robert

doi:10.1109/ultsym.2009.5441848

Cited by 12 publications

(7 citation statements)

References 12 publications

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“…For example, when SiO 2 with

Z_{l} = 1.286 \times 1 0^{7}

kg/(m 2 s) is selected as the material of coupling layer, the CRF FBW can be tuned in the range of 14.7% to 32%, the n77 and n78 band filters can be realized under this scenario. When carbon‐doped oxides (CDO) with

Z_{l} = 5.4 \times 1 0^{6}

kg/(m 2 s) 26 is adopted, the FBW can be changed from 6% to 14.5%, which satisfies the bandwidth requirement of the n79 band filter.…”

Section: Crf Synthesis Based On the Modified Crf‐bvd Modelmentioning

confidence: 99%

Synthesis of wideband bulk acoustic wave coupled resonator filter combined with lumped components

Xie

et al. 2022

Circuit Theory & Apps

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A novel wideband bulk acoustic wave (BAW) coupled resonator filter (CRF) combined with external lumped inductors and capacitors is proposed. The filter synthesis method based on the Butterworth-van Dyke (BVD) model of CRF (CRF-BVD) is also presented. To improve the synthesis accuracy, the CRF-BVD model is modified and the CRF configuration with a single rather than the traditional multiple coupling layer is adopted in this paper. By establishing equivalence relationships between the modified CRF-BVD model and the filter prototype synthesis network, exact CRF dimensions are solved through a set of equations without any further parameters tuning. The proposed method exhibits a maximum 37.4% (FBW) for a Chebyshev filter with 9.4-dB return loss, which overcomes the narrowband limitation of regular BAW filters with FBW below 5%. To demonstrate the synthesis procedure, an n77 band filter with 3.723-GHz center frequency and 24.2% FBW is designed and simulated. Good agreements are obtained among the simulation results of the prototype synthesis network, the modified CRF-BVD model, and the cosimulations of physical model based on the finite element method (FEM) and the CMOS 130-nm technology.bulk acoustic wave, coupled resonator filter, filter synthesis, wideband filter | INTRODUCTIONBulk acoustic wave (BAW) filters have been identified as one of the best filter options for front-end circuits in wireless mobile communication systems owing to their ultrasmall size, low insertion loss (IL), steep skirt selectivity, and high power handling capability. 1,2 However, the bandwidth of BAW filters is limited by the effective electromechanical coupling coefficient k 2 ef f of BAW resonators. 3,4 The k 2 ef f must be at least double the fractional bandwidth (FBW) of a radio band. Therefore, the commercialized aluminum nitride (AlN) based BAW filter with k 2 ef f less than 7% can only reach a fractional bandwidth (FBW) below 3.5%. 5 With mobile communication evolving into the 5G era, some new bands with large FBW such as n79 (12.8% FBW), n78 (14.8% FBW), and n77 (24.2% FBW) have been proposed. Such wide bandwidths are hard to achieve with regular BAW filters. 6,7 To improve the bandwidth of BAW filters, some approaches have been developed. One is adding auxiliary inductors in series/parallel with the shunt/series resonators. 8,9 However, the bandwidth cannot be extended too much due to the limited distance between the transmission zeros at the lower and upper sides of the passband. Unexpected passbands also appear in the stopband range and affect the broadband rejection performance. 10 One method is employing

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“…For example, when SiO 2 with

Z_{l} = 1.286 \times 1 0^{7}

Z_{l} = 5.4 \times 1 0^{6}

kg/(m 2 s) 26 is adopted, the FBW can be changed from 6% to 14.5%, which satisfies the bandwidth requirement of the n79 band filter.…”

Section: Crf Synthesis Based On the Modified Crf‐bvd Modelmentioning

confidence: 99%

Synthesis of wideband bulk acoustic wave coupled resonator filter combined with lumped components

Xie

et al. 2022

Circuit Theory & Apps

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“…For the commonly used piezoelectric and electrode materials, the acoustic impedance of the coupler has to be about 2-6 MRayl. A suitable material for this single-layer coupler is carbon-doped oxide (CDO) as its acoustic impedance can be adjusted by properly choosing the deposition conditions [6]. Figure 4 shows the stress distribution of the lower frequency mode in the passband, as well as the stress distribution of the upper frequency mode.…”

Section: Layer Stack Design Of Baw-crfmentioning

confidence: 99%

Bulk acoustic wave-coupled resonator filters: Concept, design, and application

Shirakawa

Thalhammer²,

Jamneala

et al. 2011

Int J RF and Microwave Comp Aid Eng

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Bulk-acoustic-wave-coupled resonator filters is an emerging technology that is capable of meeting increasingly ambitious demands of wireless applications by addressing performance, chip size, and die cost. This article outlines the fundamental design principles of these filters. A major consideration of filter design is the choice of the coupling structure between the two vertically stacked resonators. This can be either a multilayer Bragg coupler or a novel structure using a single layer of a very low acoustic impedance material. It is demonstrated how spurious modes are related to the dispersion diagram and how they affect the passband characteristics. For the suppression of these spurious modes suitable edge termination techniques are discussed. Based on optimized coupler performance and known parasitic effects, we analyze circuit design methods for microwave filters and duplexers with specific passband, roll-off, and wideband responses. We show as example a miniature 2.0 Â 1.6 mm 2 Universal Mobile Telecommunication System (UMTS) Band1 duplexer fabricated using the coupler resonator technology.

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“…at the high end of the acceptable acoustic impedance range, carbon-doped oxide materials [11] offer the benefit of a stiffer structure less prone to phonon scattering and hence the promise of a smaller acoustic attenuation. In addition, the conformal step coverage provided by the chemical vapor deposition technique used to deposit cdo should produce better coupler thickness uniformity across the resonators.…”

Section: Ultra-miniature Coupled Resonator Filter With Single-layer Amentioning

confidence: 99%

“…The cdo films are deposited by plasma-enhanced chemical vapor deposition using an industry-standard process tool. We show that the typical acoustic impedance and attenuation of our cdo coupler material [11], [12] provide a superior solution for the crF filters when compared with silK material, even though cdo has higher acoustic impedance than silK. some material properties of the coupler layer (like density and thickness) are determined through direct measurements.…”

Section: Introductionmentioning

confidence: 99%

Ultra-miniature coupled resonator filter with single-layer acoustic coupler

Jamneala

Koelle

Shirakawa

et al. 2009

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Coupled resonator filters designed using a single-layer coupler require coupling materials with an acoustic impedance less than 5.0 MRayl. Carbon-doped oxide, with an acoustic impedance of 4.8 MRayl and an acoustic attenuation of 200 to 600 dB/cm at 1 GHz, can be used as a single-layer coupler to produce a competitive 2-stage coupled resonator filter for cellular handset applications in the gigahertz frequency range. The electrical response of our filter is superior to that of coupled resonator filters using a traditional acoustic mirror as the coupling element. We present an ultra-miniature 0.58 mm x 0.38 mm coupled resonator filter operating at a frequency of 2.15 GHz.

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Improved coupled resonator filter performance using a carbon-doped oxide de-coupling layer

Cited by 12 publications

References 12 publications

Synthesis of wideband bulk acoustic wave coupled resonator filter combined with lumped components

Synthesis of wideband bulk acoustic wave coupled resonator filter combined with lumped components

Bulk acoustic wave-coupled resonator filters: Concept, design, and application

Ultra-miniature coupled resonator filter with single-layer acoustic coupler

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