An electronically tunable microstrip bandpass filter using thin-film Barium-Strontium-Titanate (BST) varactors

Nath, J.; Ghosh, Dipankar; Maria, Jon Paul; Kingon, Angus I.; Fathelbab, Wael M.; Franzon, Paul D.; Steer, M.B.

doi:10.1109/tmtt.2005.854196

Cited by 238 publications

(87 citation statements)

References 20 publications

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“…16 It is important to mention that the BST-based materials are compatible with the film technologies, so that it is common to deposit BST films with the characteristic for coatings thicknesses of several hundred microns. 17 In order to reduce the number of optimization variables, all layers of the shell are presumed to have equal thicknesses defined by the chosen outer radius 'b' of the cloak and by the number of layers. It is worth mentioning that this assumption does not prevent optimization of the thickness of the cloak layers.…”

mentioning

confidence: 99%

Spherical cloaking using multilayer shells of ordinary dielectrics

Wang¹,

Chen²,

Semouchkina³

2013

AIP Advances

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An approach for spherical cloaking using multilayer ordinary dielectric materials has been developed. The total scattering cross section (TSCS) of the spherical multilayer shell with metallic core was derived based on the Mie theory. The dielectric profile of the shell was optimized to minimize the TSCS of the cloaked target. The specific directions, at which the scattering could be practically eliminated, were detected. The influence of the target size and the dielectric material loss on the cloaking efficiency was analyzed. It was shown that the cloaking efficiency for larger targets could be improved by employing lossy materials in the shell.

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mentioning

confidence: 99%

Spherical cloaking using multilayer shells of ordinary dielectrics

Wang¹,

Chen²,

Semouchkina³

2013

AIP Advances

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“…The advantages of BST include dc voltage tunable high permittivity, high capacitance density (10-100 nF/mm 2 ), bipolar dc bias for tuning the varactor, large capacitance tuning range (>3:1), high power handling capability (>1 W), good temperature stability from 0 C to 110 C in thin films compared to bulk oxides, and quality factor in the frequency range of 1-10 GHz comparable to semiconductor varactor diodes. Applications demonstrated using BST thin film varactors include tunable filters, 8 tunable phase shifters, 9 delay lines, 10 VCO, 11 and reconfigurable antennas. 12 Table I compares the BST thin film varactor technology with semiconductor diode and the RF MEMS capacitor technologies.…”

Section: Current State Of the Art Of Multifunctional Oxide And Mumentioning

confidence: 99%

“…31 An electronically tunable microstrip combline band pass filter using thin film interdigested BST varactors was demonstrated in 2005. 8 Application of 0-200 V bias varied the central frequency of the filter from 2.44 GHz to 2.88 GHz. Kalkur et al reported the results of third order combline band pass filters implemented with parallel plate BST discrete capacitors 73 packaged using a conductive epoxy.…”

Section: Tunable Filtersmentioning

confidence: 99%

Challenges and opportunities for multi-functional oxide thin films for voltage tunable radio frequency/microwave components

Subramanyam¹,

Cole²,

Sun³

et al. 2013

Journal of Applied Physics

147

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There has been significant progress on the fundamental science and technological applications of complex oxides and multiferroics. Among complex oxide thin films, barium strontium titanate (BST) has become the material of choice for room-temperature-based voltage-tunable dielectric thin films, due to its large dielectric tunability and low microwave loss at room temperature. BST thin film varactor technology based reconfigurable radio frequency (RF)/microwave components have been demonstrated with the potential to lower the size, weight, and power needs of a future generation of communication and radar systems. Low-power multiferroic devices have also been recently demonstrated. Strong magneto-electric coupling has also been demonstrated in different multiferroic heterostructures, which show giant voltage control of the ferromagnetic resonance frequency of more than two octaves. This manuscript reviews recent advances in the processing, and application development for the complex oxides and multiferroics, with the focus on voltage tunable RF/microwave components. The over-arching goal of this review is to provide a synopsis of the current state-of the-art of complex oxide and multiferroic thin film materials and devices, identify technical issues and technical challenges that need to be overcome for successful insertion of the technology for both military and commercial applications, and provide mitigation strategies to address these technical challenges. V C 2013 AIP Publishing LLC.

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“…Alternatively, passive load modulation technique using barium-strontium-titanate (BST) varactors can be implemented [12]. Recently, thick-film BST components have demonstrated promising perspectives in terms of tunability with high-power capability [13].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of GaN-HEMT power amplifiers using BST-based components for load modulation

Arnous

Wiens

Saad

et al. 2014

Int. J. Microw. Wireless Technol.

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In this paper, the concept of load-modulated power amplifiers (PAs) is studied. Two GaN-HEMT power amplifiers (PAs), targeted for high efficiency at maximum and output back-off (OBO) power levels, are designed, implemented, and tested across 1.8-2.2 GHz. The load modulation in the first design is realized by tuning the shunt capacitors in the output matching network. A novel method is employed in the second design, where barium-stronrium-titante is used for the realization of load modulation. The large-signal measurement results across the desired band show 59-70% drain efficiency at 44-44.5 dBm output power for both designs. Using the available tunable technique, the drain efficiency of the PAs is enhanced by 4-20% at 6 dB OBO across the bandwidth. I . I N T R O D U C T I O NOwing to the rapid growth of subscribers in wireless communication systems [1] and the emergence of new communication standards, such as worldwide interoperability for microwave access (WIMAX) and 4 G long-term evolution (LTE), the mobile radio base stations (RBSs) must process different types of standards in increasing number of frequency bands. At the core of the RBS, the power amplifier (PA) is one of the most critical components since its performance affects the overall system performance in terms of output power, bandwidth, and efficiency [2,3]. Modulation schemes, such as orthogonalfrequency-division multiplexing (OFDM), and quadrature amplitude modulation (QAM) are used in modern wireless communication systems to maximize the spectral efficiency [2]. These modulation schemes result in signals with large amplitude variations and peak to average power ratios (PAPRs) in the range of 6-12 dB [4,5]. In order to prevent strong distortion of the signal, these signals require the PA to operate at an average output power far below from the saturation region and hence, at low-efficiency levels.Various techniques have been proposed to enhance the efficiency of PAs at back-off operation. Dynamic supply modulation (DSM) [6,7] and dynamic load modulation (DLM) [8] have proven themselves to be the most promising methods. The DSM method requires efficient DC/DC converter as well as efficient envelope tracking amplification, whereas the DLM may be realized using extra active devices as implemented in Doherty amplifiers [9] or using passive components [10]. In terms of cost, complexity, and additional power consumption, DLM using passive components seems to be more efficient than DSM and Doherty amplifiers in spite of the challenges in the dynamic range of power detector and the required speed to follow the envelope variation. DLM can be realized by tunable matching networks (TMNs) using conventional passive components such as micro-electro-mechanical systems (MEMS) [10] semiconductor or ferroelectric-based varactors [11]. Alternatively, passive load modulation technique using barium-strontium-titanate (BST) varactors can be implemented [12]. Recently, thick-film BST components have demonstrated promising perspectives in terms of tunability with high...

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An electronically tunable microstrip bandpass filter using thin-film Barium-Strontium-Titanate (BST) varactors

Cited by 238 publications

References 20 publications

Spherical cloaking using multilayer shells of ordinary dielectrics

Spherical cloaking using multilayer shells of ordinary dielectrics

Challenges and opportunities for multi-functional oxide thin films for voltage tunable radio frequency/microwave components

Evaluation of GaN-HEMT power amplifiers using BST-based components for load modulation

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