• Title/Summary/Keyword: crystal resonator

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FBAR Devices Fabrication and Effects of Deposition Temperature on ZnO Crystal Growth for RF Filter Applications (RF 필터응용을 위한 FBAR 소자제작과 증착온도가 ZnO 박막의 결정성장에 미치는 영향)

  • Munhyuk Yim;Kim, Dong-Hyun;Dongkyu Chai;Mai Linh;Giwan Yoon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2003.05a
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    • pp.88-92
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    • 2003
  • In this paper, the characteristics of the ZnO films deposited on AI bottom electrode and the temperature effects on the ZnO film growth are presented along with the fabrication and their evaluation of the film bulk acoustic wave resonator (FBAR) devices. All the films used in this work were deposited using a radio-frequency (RF) magnetron sputtering technique. Growth characteristics of the ZnO films are shown to have a strong dependence on the deposition temperatures ranged from room temperature to 35$0^{\circ}C$ regardless of the RF power applied for sputtering the ZnO target. In addition, according to the growth characteristics of the distinguishably different micro-crystal structures and the degree of the c-axis preferred orientation, the deposition temperatures can be divided into 3 temperature regions and 2 critical temperatures in-between. Overall, the ZnO films deposited at/below 20$0^{\circ}C$ are seen to have columnar grains with a highly preferred c-axis orientation where the full width at half maximum (FWHM) of X-ray diffraction rocking curve is 14$^{\circ}$. Based on the experimental findings, several FBAR devices were fabricated and measured. As a result, the FBAR devices show return loss of ~19.5dB at resonant frequency of ~2.05GHz.

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Microwave Dielectric Characteristics of Ba(Mg1/3Nb2/3)O3-La(Mg2/3Nb1/3)O3 Ceramics with Crystal Structure (결정 구조에 따른 Ba(Mg1/3Nb2/3)O3-La(Mg2/3Nb1/3)O3세라믹스의 마이크로파 유전 특성)

  • Paik, Jong-Hoo;Lim, Eun-Kyeong;Lee, Mi-Jae;Jee, Mi-Jung;Choi, Byung-Hyun;Kim, Sei-Ki
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.1
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    • pp.30-37
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    • 2005
  • The microwave dielectric properties and their related structural characteristics in solid solutions of (1-$\chi$) Ba($Mg_{1/3}$Nb$_{2/3}$) $O_3$-$\chi$La(Mg$_{2/3}$Nb$_{1}$3) $O_3$(BLMN) have been investigated by measuring the dielectric constant($\varepsilon$r), Q value and temperature coefficient of resonant frequency($\tau$f) and by observing the crystal structure using high resolution transmission electron microscopy (HRTEM). Microwave dielectric properties showed characteristic features for specific composition. Dielectric constant($\varepsilon$$_{r}$) showed maximum value at the composition which corresponds to the phase boundary between 1 : 2 ordered and 1 : 1 ordered structure. The increase in $\varepsilon$$_{r}$ may be caused by the rattling of ions by incorporating smaller ions and the disordered structure. The variation of temperature coefficient of resonant frequency($\tau$$_{f}$) was investigated in terms of oxygen octahedra tilting.dra tilting.

Design of Local Oscillator with Low Phase Noise for Ka-band Satellite Transponder (Ka-band 위성 중계기용 저위상잡음 국부발진기의 설계 및 제작)

  • 류근관;이문규;염인복;이성팔
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.6
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    • pp.552-559
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    • 2002
  • The EM(Engineering Model) LO(Local Oscillator) is designed for Ka-band satellite transponder. The VCO(Voltage Controlled Oscillator) is implemented using a high impedance inverter coupled with dielectric resonator to improve the phase noise performance out of the loop bandwidth. The phase of VCO is locked to that of a stable OCXO(Oven Controlled Crystal Oscillator) by using a SPD(Sampling Phase detector) to improve phase noise performance in the loop bandwidth. This LO exhibits the harmonic rejection characteristics above 43.83 dBc and requires 15 V and 160 mA. The phase noise characteristics are performed as -102.5 dBc/Hz at 10 KHz offset frequency and -104.0 dBc/Hz at 100 KHz offset frequency, respectively, with the output power of 13.50 dBm$\pm$0.33 dB over the temperature range of -20~+7$0^{\circ}C$.

A femtosecond Cr:LiSAF laser pumped by semiconductor lasers (반도체 레이저 여기 펨토초 Cr:LiSAF 레이저)

  • 박종대
    • Korean Journal of Optics and Photonics
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    • v.11 no.5
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    • pp.360-364
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    • 2000
  • We demonstrate self-starting passIve mode locking of a Cr:LiSAF laser, using a SCIDlconduclor Saturable Absorber Mirror (SESAM), Two high-power red semiconductor lasers (Coherent S-67-500C-100-H) of wavelength 667 nm and maximum power of 500 mW were used as pump lasers, The cavity has 10 cm radius-ai-curvature folding minors, two SF 10 prisms, a 99% reflectivity output coupler and a SESAM at dIe focus of a 10 cm radIus-at-curvature mirror. We used the laser crystal in BrewsterBrewster shape with 1 5% $Cr^{+3}$ ion concentration and the length of 6 mm, An X-shaped resonator was used to compensate the astigmatism induced by tile crystal. The structure of the SESAM cOllSists of 30 pmr of $AlAs/Al_{0.15}Ga_{0.85}As$ layer, wi1l1 a 10 nm GaAs quantum well situated in the topmost layer Output spectra were centeled at 833 nm, with 4 nm spectral bandwidth and pulse width was measured to be 220 fs, Output power of 3 mW is obtained at a pump power of 800 mW. 00 mW.

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New Configuration of a PLDRO with an Interconnected Dual PLL Structure for K-Band Application

  • Jeon, Yuseok;Bang, Sungil
    • Journal of electromagnetic engineering and science
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    • v.17 no.3
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    • pp.138-146
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    • 2017
  • A phase-locked dielectric resonator oscillator (PLDRO) is an essential component of millimeter-wave communication, in which phase noise is critical for satisfactory performance. The general structure of a PLDRO typically includes a dual loop of digital phase-locked loop (PLL) and analog PLL. A dual-loop PLDRO structure is generally used. The digital PLL generates an internal voltage controlled crystal oscillator (VCXO) frequency locked to an external reference frequency, and the analog PLL loop generates a DRO frequency locked to an internal VCXO frequency. A dual loop is used to ease the phase-locked frequency by using an internal VCXO. However, some of the output frequencies in each PLL structure worsen the phase noise because of the N divider ratio increase in the digital phase-locked loop integrated circuit. This study examines the design aspects of an interconnected PLL structure. In the proposed structure, the voltage tuning; which uses a varactor diode for the phase tracking of VCXO to match with the external reference) port of the VCXO in the digital PLL is controlled by one output port of the frequency divider in the analog PLL. We compare the proposed scheme with a typical PLDRO in terms of phase noise to show that the proposed structure has no performance degradation.

Role of Am Piezoelectric Crystal Orientation in Solidly Mounted Film Bulk Acoustic Wave Resonators

  • Lee, Si-Hyung;Kang, Sang-Chul;Han, Sang-Chul;Ju, Byung-Kwon;Yoon, Ki-Hyun;Lee, Jeon-Kook
    • Journal of the Korean Ceramic Society
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    • v.40 no.4
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    • pp.393-397
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    • 2003
  • To investigate the effect of AIN c-axis orientation on the resonance performance of film bulk acoustic wave resonators, solidly mounted resonators with crybtallographically different AIN piezoelectric films were prepared by changing only the bottom electrode surface conditions. As increasing the degree of c-axis texturing, the effective electromechanical coupling coefficient ($\kappa$$\_$eff/)$^2$ in resonators increased gradually. The least 4 degree of full width at half maximum in an AIN(002) rocking curve, which corresponds to $\kappa$$^2$$\_$eff/ of above 5%, was measured to be necessary for band pass filter applications in wireless communication system. The longitudinal acoustic wave velocity of AIN films varied with the degree of c-axis texturing. The velocity of highly c-axis textured AIN film was extracted to be about 10200 n/s by mathematical analysis using Matlab.

Structural and Microwave Dielectric Properties of BMT-BCN Ceramics (BMT-BCN 세라믹의 구조 및 마이크로파 유전특성)

  • Lee, Moon-Kee;Park, In-Gil;Ryu, Ki-Won;Lee, Young-Hie
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1453-1455
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    • 1998
  • $Ba(Mg,Ta)O_3-Ba(Co,Nb)O_3$ ceramics were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of 1500-$1575^{\circ}C$ for 5[hr.] in air. The crystal structure was investigated by the XRD. The microstructure of the ceramics were observed by SEM. The microwave properties of dielectric resonators were investigated as a function of composition and sintering temperature. $Ba(Mg,Ta)O_3-Ba(Co,Nb)O_3$ ceramics have a structure of complex perovskite type, and have peaks of (101),(102),(201),(202) and (212). In the case of the $0.7Ba(Mg,Ta)O_3-0.3Ba(Co,Nb)O_3$ ceramic resonator, dielectric constant, quality factor and temperature coefficient of resonant frequency(TCRF, ${\tau}_l$) were a good value of 26.5, 11.500 at 10[GHz] and -1.3[ppm/$^{\circ}C$] from $25^{\circ}C$ to $60^{\circ}C$, respectively.

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Structure and Dielectric Properties of $(Ba_{1-x}Ca_x)(Mg_{1/3}Ta_{2/3})O_3$ Ceramics ($(Ba_{1-x}Ca_x)(Mg_{1/3}Ta_{2/3})O_3$ 세라믹스의 구조와 유전특성)

  • Cho, Jung-Ho;Cho, Jong-Rae;Kim, Kang-Eun;Chung, Su-Tae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.05b
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    • pp.167-170
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    • 2000
  • The structural changes and the dielectric properties of $(Ba_{1-x}Ca_x)(Mg_{1/3}Ta_{2/3})O_3$ (x=0, 0.2, 0.4, 0.6, 0.8, 1) were investigated. The densities of samples were gradually decreased with increasing x, (BMT=7.69, CMT=5.25 $g/cm^3$). The crystal structure of BMT was a untiltied perovskite structure, however BCMT showed antiphase tilting and antiphase-inphase tilting structure. The dielectric constant($\varepsilon_r$) of the highest value was 33 at x=0.2 (BMT=24, CMT=17). The maximum quality factor was 27,500GHz in BMT. The quality factor· of BCMT was decreased to x<0.2 (5,000GHz), and was gradually increased to x>0.2. The temperature coefficients of dielectric constant was positive at x<0.8, and negative in CMT.

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The Effect of Mg Deficiency on the Microwave Dielectric Characteristics of (Mg1/2Nb2/3)O3 Ceramics (Mg 결핍에 따른 Ba(Mg1/2Nb2/3)O3 세라믹스의 마이크로파 유전특성)

  • Paik, Jong-Hoo;Lee, Mi-Jae;Choi, Byung-Hyun;Kim, Hyo-Tae;Jee, Mi-Jung;Lim, Eun-Kyeong;Nahm, Sahn;Lee, Hwack-Joo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.4
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    • pp.384-389
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    • 2004
  • Crystal structure and microwave dielectric properties of Ba(Mg1/3Nb2/3) $O_3$ (BMN) ceramics were investigated. Ba(Mg1/3Nb2/3) $O_3$ has the 1:2 ordered hexagonal structure. The 1:2 ordering and relative density of specimens increased with small Mg deficiency(x). The variation of Q${\times}$ $f_{0}$ with Mg deficiency is very similar to that of 1:2 ordering and relative density. The highest Q${\times}$ $f_{0}$ achieved in this investigation is about 96,000 for Ba(Mg1/3Nb2/3) $O_3$. The improvement of Q${\times}$ $f_{0}$ with Mg-deficiency is related to the increase of degree of ordering and relative density of the specimen.

The Effect of Mg Deficiency on the Microwave Dielectric characteristics of $Ba(Mg_{1/3}Nb_{2/3})O_3$ Ceramics (Mg 결핍에 따른 $Ba(Mg_{1/3}Nb_{2/3})O_3$ 세라믹스의 마이크로파 유전특성)

  • Paik, Jong-Hoo;Lee, Mi-Jae;Choi, Byung-Hyun;Lee, Jong-Won;Jee, Mi-Jung;Lim, Eun-Kyeong;Nahm, Sahn;Lee, Hwack-Joo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.11a
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    • pp.46-50
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    • 2003
  • Crystal structure and microwave dielectric properties of $Ba(Mg_{1/3-x}Nb_{2/3})O_3$ (BMN) ceramics were investigated. $Ba(Mg_{1/3}Nb_{2/3})O_3$ has the 1:2 ordered hexagonal structure. The 1:2 ordering and relative density of specimens increased with small Mg deficiency(x). The variation of Q-value with Mg deficiency is very similar to that of 1:2 ordering and relative density. The highest $Q{\times}f_0$ achieved in this investigation is about 96,000 for $Ba(Mg_{1/3-0.02}Nb_{2/3})O_3$. The improvement of Q-value with Mg-deficiency is related to the increase of degree of ordering and relative density of the specimen.

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