• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.250-256
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• 2008

In this paper, an X-band oscillator is presented using a new miniaturized microstrip hairpin resonator. The newly designed hairpin resonator on the microstrip line employs the spiral structure, which shows a higher loaded quality factor and the 50 % reduced circuit area compared to the conventional one at 9.2 GHz. The oscillator using proposed resonator shows the output power of 10.87 dBm, the second harmonic suppression of 41.99 dBc, and the phase noise performance of -101.49 dBc/Hz at 100 kHz offset, which is better than the conventional resonator oscillator by 6.17 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.820-825
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• 2004

In this paper an octave tuning voltage controlled oscillator which is used in set-top TV tuner was designed. Oscillation frequency range is 0.9 GHz～2.2 GHz with 1.3 GHz bandwidth. By using 4 varactor diodes in base and emitter of transistor, wide-band tuning, sweep linearity and low phase noise could be achieved. Designed VCO requires a tuning voltage of 0 V ～ 20 V and DC consumption of 10 V and 15 mA. Designed VCO exhibits an output power of 5.3 dBm $\pm$1.1 dB and a phase noise below -94.8 dBc/Hz ＠ 10 kHz over the entire frequency range. The sweep linearity shows 65 MHz/V with a deviation of $\pm$10 MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.241-247
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• 2007

This paper introduces a new type push-push harmonic dielectric resonator oscillator. Proposed oscillators are utilized by HDRO(Harmonic Dielectric Resonator Oscillator) which are combined in push-push structure. As a result, fundamental signal suppression ratio and output power of harmonic signal has been improved. The increase of phase noise is compensated by improving coupling characteristic between resonator and parallel microstrip line. The proposed push-push HDRO shows the output power of 9.32 dBm, the fundamental signal suppression of -47.2 dBc and phase noise of -99.86 dBc at 100 kHz offset frequency and 18.7 GHz center frequency.

• Journal of electromagnetic engineering and science
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• v.4 no.3
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• pp.137-142
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• 2004

In this paper, we present a new current-current negative feedback(CCNF) differential voltage-controlled oscillator (VCO) with 1/f induced low-frequency noise suppressed. By means of the CCNF, the 1/f induced low-frequency noise is removed from the proposed CCNF VCO. Also, high-frequency noise is stopped from being down-converted into phase noise by means of the increased output impedance through the CCNF and the feedback capacitor $C_f. The proposed CCNF VCO represents 11-dB reduction in phase noise at 10 kHz offset, compared with the conventional differential VCO. The phase noise of the proposed CCNF VCO is measured as - 87 dBc/Hz at 10 kHz offset frequency from 5.5-GHz carrier. The proposed CCNF VCO consumes 14.0 mA at 2.0 V supply voltage, and shows single-ended output power of - 12 dBm.

• Journal of IKEEE
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• v.3 no.1 s.4
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• pp.39-49
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• 1999

This paper describes a 1 GHz, low-phase-noise CMOS fractional-N frequency synthesizer with an integrated LC VCO. The proposed frequency synthesizer, which uses a high-order delta-sigma modulator to suppress the fractional spurious tones at all multiples of the fractional frequency resolution offset, has 64 programmable frequency channels with frequency resolution of $f_ref/64$. The measured phase noise is as low as -110 dBc/Hz at a 200 KHz offset frequency from a carrier frequency of 980 MHz. The reference sideband spurs are -73.5 dBc. The prototype is implemented in a $0.5{\mu}m$ CMOS process with triple metal layers. The active chip area is about $4mm^2$ and the prototype consumes 43 mW, including the VCO buffer power consumption, from a 3.3 V supply voltage.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.413-414
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• 2008

A 2.4 GHz low phase noise fully integrated LC voltage-controlled oscillator (VCO) in $0.18\;{\mu}m$ CMOS technology is presented in this paper. The VCO is optimized based on phase noise reduction. The design of the VCO uses differential varactors which are adopted for symmetry of the circuit, and consider AM-PM conversion due to a cross-coupled pair. The VCO is designed to draw 3 mA from 1.8 V supply voltage. Simulated phase noise is -137.3 dBc/Hz at 3 MHz offset. The tuning range is found to be 300 MHz range from 2.3 GHz to 2.6 GHz.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2333-2335
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• 2005

Various CMOS quadrature-voltage-controlled oscillators(QVCOs) are designed and fabricated for the comparison of the phase noise. The core VCO is composed of two Colpitts oscillators which are cross-coupled with PMOS pair. For the comparison of phase noise with the proposed scheme, the conventional LC VCO followed by the frequency-divide-by-two is designed. The simulation result demonstrate that the proposed scheme shows better phase noise performance by 6dB than that of a conventional scheme in which LC VCO is followed by the frequency-divide-by-two.

• Journal of Advanced Navigation Technology
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• v.6 no.1
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• pp.52-62
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• 2002

Electrical characteristics of two types of 20 GHz Push-Push GaAs MESFET dielectric resonator oscillators having Wilkinson and T-junction power combiners for the output stage have been investigated. The Push-Push oscillator for suppressing fundamental frequency 10 GHz and enhancing 20 GHz has been designed and realized in microstrip configuration on 20 mil thick RT-Duroid(${\varepsilon}_r$=2.52) teflon substrate. Two different types of power combiners, T-junction and Wilkinson, have been considered. Whenever one type of the combiners has been adopted for the output circuit, output power, phase noise and fundamental frequency suppression characteristics of the oscillator have been measured. When the Wilkinson power combiner was used, a maximum output power of 5.67 dBm, a phase noise of -105.5 dBc/Hz at an offset frequency of 100 kHz and a fundamental frequency suppression of -29.33 dBc have been measured. When the T-junction power combiner was used, a maximum output power of -1.17 dBm, a phase noise of -102.2 dBc/Hz at an offset frequency of 100 kHz and a fundamental frequency suppression of -17.84 dBc have been measured.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.3
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• pp.313-321
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• 2014

A low-power low-cost polar transmitter for EDGE is designed in $0.18{\mu}m$ CMOS. A differential delta-sigma modulator (DSM) tunes a three-terminal voltage-controlled oscillator (VCO) to perform RF phase modulation, where the VCO tuning curve is digitally pre-compensated for high linearity and the carrier frequency is calibrated by a dual-mode low-power frequency-locked loop (FLL). A digital intermediate-frequency (IF) pulse-width5 modulator (PWM) drives a complementary power-switch followed by an LC filter to achieve envelope modulation with high efficiency. The proposed transmitter with 9mW power dissipation relaxes the time alignment between the phase and envelope modulations, and achieves an error vector magnitude (EVM) of 4% and phase noise of -123dBc/Hz at 400kHz offset frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.122-128
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• 2005

In this paper, a low noise parallel feedback oscillator for harmonic suppression and a frequency doubler are designed and implemented. As the fundamental signal of the oscillator for frequency doubling is extracted between the dielectric resonator (DR) filter and the gate device of the active device, the undesired harmonics at the output of the oscillator is remarkably suppressed. The fundamental signal of the oscillator for frequency doubling directly feeds to the frequency doubler without an additional band pass filter for harmonic suppression. The second harmonic suppression of -47.7 dBc at the oscillator output is achieved, while the fundamental suppression of -37.5 dBc at the doubler output is obtained. The phase noise characteristics are -80.3 dBc/Hz and -93.5 dBc/Hz at the offset frequency of 10 KHz and 100 KHz from the carrier, respectively.