• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.4
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• pp.468-474
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• 2012

A low phase-noise microwave oscillator is presented by a substrate integrated waveguide(SIW) loading a complementary split ring resonator(CSRR) in this paper. The unloaded $Q$-factor of the SIW cavity is increased by loading a complementary split ring resonator(CSRR) and its value exhibits 1960. It is theoretically and experimentally demonstrated that the proposed circuit generates 11.3 dBm of output power at 9.3 GHz and a phase-noise of -127.9 dBc/Hz at 1-MHz offset.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.311-320
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• 2008

In this paper, a new variable active inductor using a conventional grounded active inductor with feedback variable LC-resonator is proposed. The grounded active inductor is realized by the gyrator-C topology and the variable LC-resonator is realized by the low-Q spiral inductor and varactor. This variable LC-resonator can compensate the degradation of Q-factor due to parasitic capacitance of a transistor, and the frequency range with high Q-factor is adjustable by resonance frequency adjustment of LC-resonator. The fabricated variable active inductor with Magnachip $0.18{\mu}m$ CMOS process shows that high-Q frequency range can be adjusted according to varactor control voltage from 4.66 GHz to 5.45 GHz and Q-factor is higher than 50 in the operating frequency ranges. The measured inductance at 4.9GHz can be controlled from 4.12 nH to 5.97 nH by control voltage.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.7
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• pp.77-80
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• 2008

In this paper, low phase noise VCO using novel compact microstrip spiral resonator is proposed. A spiral resonator has super compact dimension, low insertion losses in the passband and high level of rejection in the stopband with sharp cutoff and a large coupling coefficient value, which makes a high Q value, and has reduced the phase noise. To increase the tuning range of VCO, varactor diode has been connected at the tunable negative resistance in VCO. This VCO has presented the oscillation frequency of $5.686{\sim}5.841GHz$, harmonics -29.83 dBc and phase noise of $-115.16{\sim}-115.17dBc/Hz$ at the offset frequency of 100 KHz.

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.47-47
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• 2002

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.5
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• pp.89-96
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• 2012

In this paper, a low phase noise oscillator is designed using an interdigital hairpin resonator for UTIS (Urban Traffic Information Systems). The interdigital hairpin resonator has several characteristics compared with a conventional hairpin resonator, which are 70% size reduction and improvement of harmonic characteristics. In addition, Q (Quality factor) of the interdigital hairpin resonator is about 132, which is suitable for the design of a low phase noise oscillator. The oscillator suggested in this paper shows the output power of 12 dBm and the phase noise characteristic of -100.8 dBc/Hz at 100 kHz offset frequency from the center frequency of 5.75 GHz. The phase noise is improved by about 12 dB compared with a conventional oscillator using an interdigital hairpin resonator.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.1-5
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• 2009

In this paper, low phase noise push-push oscillator (OSC) using the metamaterial resonator for missile defense systems and satellite communication was design and implemented. The metamaterial resonator has the large coupling coefficient value, which makes a high Q value, and has reduced phase noise of OSC. The OSC with 1.8 V power supply has phase noise of -117 dBc/Hz @100 kHz in the 12 GHz. When it has been compared with metamaterial resonator and coventional spiral resonator, the reduced Q value has been -29.7 dB and -47.6 dB respectively. This low phase noise OSC using metamaterial resonator could be available to a OSC in X-band.

• Journal of electromagnetic engineering and science
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• v.5 no.4
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• pp.204-207
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• 2005

In this paper, PBG structure and feedforward circuit has been used to suppress the phase noise of the oscillator. Microstrip line resonator have low Q, but we can obtain high LO power by feedforward circuit and improve the resonator Q by the PBG, simultaneously. The proposed oscillator which uses PBG and feedforward circuit shows 0${\~}$20 dB phase noise reduction compared to the conventional oscillator. We have obtained -115.8 dBc of phase noise at 100 kHz offset from 2.4 GHz center.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.62-66
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• 2010

In this article, a oscillator at X-band with a double H-shape metamaterial resonator (DHMR) based on high-Q is proposed with metamaterial structure to improve Ihe phase noise and output power. The proposed oscillator is required low phase noise and high output power for the high performance frequency synthesizer. DHMR is designed to be high-Q at resonance frequency through strong coupling of E-field. This character makes phase noise excellent. The oscillator using DHMR is oscillated in X-band so as to apply frequency synthesizer of radar systems. The output power is 4.33 dBm and the phase noise is -108 dBc/Hz at 100 kHz offset of carrier frequency.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.75-82
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• 1999

TE$_{01\;{\delta}}$ mode Cavity Resonators with a low loss dielectric rod and YBa$_2Cu_3O_{7-{\delta}}$ (YBCO) endplates were prepared and their microwave properties were studied at temperatures above 30 K. Both sapphire and rutile were used as the dielectrics. The TE$_{01\;{\delta}}$ mode Q$_0$ of the resonator, designed to work as a tunable resonator with variations in the gap distance (s) between the dielectric rod and the top YBCO, was more than 1000000 at s = 0 mm and at 30 K and .the resonant frequency of 19.56GHz when a sapphire rod was used for the dielectric. The TE$_2Cu_3O_{7-{\delta}}$ mode resonant frequency (f$_0$) appeared to decrease as the temperature is raised. Meanwhile, the temperature dependence of the TE$_2Cu_3O_{7-{\delta}}$ mode f$_0$ of the rutile-loaded resonator appeared different with f$_0$ increasing according to the temperature and Q$_0$ more than 300000 at 30 K and f$_0$ = 8.56 CHz. Comparisons were made between the microwave properties of the sapphire-loaded and the rutile-loaded resonators. Also, applications of the TE$_2Cu_3O_{7-{\delta}}$ mode cavity resonator for a tunable resonator with a very high Q$_0$ as · well as a characterization tool for surface resistance measurements of HTS films are described.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.7 s.337
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• pp.63-70
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• 2005

We investigated the phase noise of an oscillator with a extremely high-Q resonator used as the resonant element. A TE$_{011}$ mode rutile-loaded resonator with high-temperature superconductive (HTS) $YBa_2Cu_3O_{7-\delta}$(YBCO) films used as the endplates is prepared for this purpose. At 23.5 K, the unloaded Q and the loaded Q are 863000 and 180000, respectively. The phase noise of -104.8 dBc/Hz at 1 KHz offset was observed for the oscillator having a resonator with $Q_{L}$ =180000 at the $TE_{01\delta$ mode resonant frequency of 8.545 GHz at 23.5 K Such oscillators with very low phase noise are expected to be used for building up communication systems capable of efficient use of the frequency band and high-speed data transmission as well as for Doppler radars. Frequency tuning could be realized for the resonator by using a piezoactuator Applicability of the tunable rutile resonator for fabricating tunable oscillators of high performances is discussed.