Tunable Ferroelectric Capacitor-Based Voltage-Controlled Oscillator

Jamil, Asad; Kalkur, T. S.; Cramer, N.

doi:10.1109/tuffc.2007.314503

Cited by 37 publications

(24 citation statements)

References 9 publications

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“…85 Jamil et al used BST varactors in differential VCOs and the configuration is shown in Figure 27. 11 This VCO has a tuning range from 205 MHz to 216.3 MHz with a power dissipation of 5.1mW. The measured phase noise is À90 dBc/MHz at 100 kHz and À140 dBc/Hz at 1 MHz.…”

Section: Vcosmentioning

confidence: 94%

“…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%

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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

145

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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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Section: Vcosmentioning

confidence: 94%

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

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

145

View full text Add to dashboard Cite

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“…The ferroelectricity is caused by the fact that the Bsite inversion symmetry is broken by the B-site substitution. For clarity, we show the local structures of LaAlO 3 and La 2 CoAlO 6 to understand the direction of polarization. A 10-atom La 3 Al 4 O 3 cluster in the R3c LaAlO 3 forms a tetrahedral structure.…”

Section: General Design Guidelinesmentioning

confidence: 99%

“…12 The typical example of the conventional improper FEs is hexagonal manganite YMnO 3 , 13 where the FE buckling (P mode) of the Y-O planes is induced by the non-polar MnO 5 polyhedra tilt (Q mode). 13,14 The free energy expansion in this system contains the coupling term (PQ 3 ) between the Q and P, indicating that the non-polar distortion Q must be reversed. 15 The hybrid improper ferroelectricity (HIF) was recently discovered in the artificial superlattice PbTiO 3 /SrTiO 3 , 16 where the ferroelectricity is induced by a trilinear coupling (PQ 1 Q 2 ) between the FE mode (P) and two oxygen octahedral rotational modes (Q 1 and Q 2 , respectively).…”

Section: Introductionmentioning

confidence: 98%

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Designing new ferroelectrics with a general strategy

Xiang

2017

npj Quant Mater

104

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The presence of a switchable spontaneous electric polarization makes ferroelectrics ideal candidates for the use in many applications such as memory and sensors devices. Since known ferroelectrics are rather limited, finding new ferroelectric materials has become a flourishing field. One promising route is to design the improper ferroelectrics. However, previous approach based on the Landau theory is not easily adopted for systems that are unrelated to the Pbnm perovskite structure. To this end, we develop a general design rule that is applicable to any system. By combining this rule with the density functional theory calculations, we identify previously unrecognized classes of ferroelectric materials. It is shown that the R3c perovskite structure can become ferroelectric by substituting half of the B-site cations. Compound ZnSrO 2 with a non-perovskite layered structure can also be ferroelectric through the anion substitution. Moreover, our approach can be used to design new multiferroics as illustrated in the case of fluorine substituted LaMnO 3 . 13 where the FE buckling (P mode) of the Y-O planes is induced by the non-polar MnO 5 polyhedra tilt (Q mode). 13,14 The free energy expansion in this system contains the coupling term (PQ 3 ) between the Q and P, indicating that the non-polar distortion Q must be reversed. 15 The hybrid improper ferroelectricity (HIF) was recently discovered in the artificial superlattice PbTiO 3 /SrTiO 3 , 16 where the ferroelectricity is induced by a trilinear coupling (PQ 1 Q 2 ) between the FE mode (P) and two oxygen octahedral rotational modes (Q 1 and Q 2 , respectively). The HIF was also found in the double-layered Ruddlesden-Popper (RP) perovskite A 3 B 2 O 7 (A=Ca, Sr; B=Mn,Ti), 17-19 the 1:1 A-cation ordering perovskite-type superlattice, 20-23 A-cation ordering RP NaRTiO 4 (R = Y, La, Nd, Sm-Ho), 24 the 2:2 B-cation ordered superlattice, 25 and metal-organic perovskite material. 26 In the above-mentioned theoretically designed FEs, one usually starts from a high-symmetry structure (e.g., cubic perovskite structure), then the effect of atomic substitution and soft phonon modulations are examined to see whether the ferroelectricity can be induced or not. Finally, the trilinear coupling mechanism is discussed to understand the origin of improper ferroelectricity. This procedure is indeed informative. However, it is tedious and its applicability to other type of compounds is limited since even the

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Circuit and System Applications of Tunable Ferroelectric Devices

2009

Engineering Materials and Processes

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This chapter looks at circuit and systems applications of ferroelectrics. Voltage Controlled Oscillators (VCO) based on ferroelectric varactors with low phase noise, extended tuning range and linear dependences of the oscillation frequency on the DC bias are discussed. Use of ferroelectric varactors in power amplifiers is reviewed where they allow increasing in the efficiency, linearity and help reducing the current consumption. Representative electronically scanning cost effective beamformers and phased array antennas are presented.

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Tunable Ferroelectric Capacitor-Based Voltage-Controlled Oscillator

Cited by 37 publications

References 9 publications

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

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

Designing new ferroelectrics with a general strategy

Circuit and System Applications of Tunable Ferroelectric Devices

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