• 한국전자파학회논문지
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• 제18권8호
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• pp.854-861
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• 2007

본 논문에서는 radar detector에 사용 가능한 국부 발진단용 소형화된 L 모양 shorted pin patch를 제안하였다. Shorted pin patch는 일반적인 구형 patch가 가지는 open-open 공진 형태가 아닌 short-open 공진 형태를 가지고 작동한다. L모양의 shorted pin 배열은 기본 모드(X-band), $2^{nd}\;and\;3^{rd}$ 모드에서 ${\lambda}/4$ 및 $3{\lambda}/4$의 공진 구조를 가지게 되어 일반적인 구정 patch보다 소형화가 가능하다 최적화된 L 모양 소정 shorted pin patch는 국부 발진단의 발진 주파수 대역(X, K and Ka band)에서 공진이 일어나 향상된 반사 손실을 가지게 되고, 이에 따라 기존 대비 향상된 radar detector의 감도는 얻을 수 있을 것으로 예상된다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
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• pp.3-6
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• 2004

This paper. we investigate the OFDM-based wireless LAN systems operating in the 60 GHz frequency band as part of the fourth-generation (4G) systems. The 60 GHz band is of much interest since this is the band in which a massive amount of spectral space (5 GHz) has been allocated worldwide for dense wireless local communications. This paper gives an overview of 60 GHz indoor wireless channel characteristics and an effect on phase noise. The performance of OFDM system is severely degraded by the local oscillator phase noise, which causes both common phase error and inter-carrier interference. We provide the exact analysis of the phase noise effect on the OFDM system.

• International Journal of Control, Automation, and Systems
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• 제4권4호
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• pp.456-465
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• 2006

The problem of recursive filtering far linear discrete-time systems with uncertainties is considered. A new suboptimal filtering algorithm is herein proposed. It is based on the fusion formula, which represents an optimal mean-square linear combination of local Kalman estimates with weights depending on cross-covariances between local filtering errors. In contrast to the optimal weights, the suboptimal weights do not depend on current measurements, and thus the proposed algorithm can easily be implemented in real-time. High accuracy and efficiency of the suboptimal filtering algorithm are demonstrated on the following examples: damper harmonic oscillator motion and vehicle motion constrained to a plane.

• 한국통신학회논문지
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• 제13권3호
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• pp.239-254
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• 1988

현대 통신에서 혼신방지및 보안유지를 위한 방법으로 ECCM기법이 개발되었다. 주파수 도약방식은 이러한 기법중의 하나이며 RF변조된 신호를 일정한 대역폭내에서 빠르게 움직여 신호의 추적을 어렵게 만드는 방법이다. 본 논문에서는 1.25MHz-800Hz의 FM변조된 기준 신호와 LO(Local Oscillator)에 의해 30-80MHz의 FM출력을 얻을 수 있는 PLL-Exciter를 구성하였다. Exciter의 LO로는 42.5-100.5 MHz에서 도약시킬 수 있는 주파수 합성기를 사용하였다.

• Journal of electromagnetic engineering and science
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• 제9권2호
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• pp.98-104
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• 2009

An InGaP/GaAs MMIC LC VCO designed with Harmonic Noise Frequency Filtering(HNFF) technique is presented. In this VCO, internal inductance is found to lower the phase noise, based on an analytic understanding of phase noise. This VCO directly drives the on-chip double balanced mixer to convert RF carrier to IF frequency through local oscillator. Furthermore, final power performance is improved by output amplifier. This paper presents the design for a 1.721 GHz enhanced LC VCO, high power double balance mixer, and output amplifier that have been designed to optimize low phase noise and high output power. The presented asymmetric inductance tank(AIT) VCO exhibited a phase noise of -133.96 dBc/Hz at 1 MHz offset and a tuning range from 1.46 GHz to 1.721 GHz. In measurement, on-chip down-converter shows a third-order input intercept point(IIP3) of 12.55 dBm, a third-order output intercept point(OIP3) of 21.45 dBm, an RF return loss of -31 dB, and an IF return loss of -26 dB. The RF-IF isolation is -57 dB. Also, a conversion gain is 8.9 dB through output amplifier. The total on-chip down-converter is implanted in 2.56${\times}$1.07 mm$^2$ of chip area.

• International journal of advanced smart convergence
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• 제9권1호
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• pp.172-176
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• 2020

The implementation of a low phase noise voltage controlled oscillator (VCO) is important for the signal integrity of wireless communication terminal. A low phase noise wideband VCO for a wireless local area network (WLAN) application is presented in this paper. A 6-bit coarse tune capacitor bank (capbank) and a fine tune varactor are used in the VCO to cover the target band. The simulated oscillation frequency tuning range is from 8.6 to 11.6 GHz. The proposed VCO is desgned using 65 nm CMOS technology with a high quality (Q) factor bondwire inductor. The VCO is biased with 1.8 V VDD and shows 9.7 mA current consumption. The VCO exhibits a phase noise of -122.77 and -111.14 dBc/Hz at 1 MHz offset from 8.6 and 11.6 GHz carrier frequency, respectively. The calculated figure of merit(FOM) is -189 dBC/Hz at 1 MHz offset from 8.6 GHz carrier. The simulated results show that the proposed VCO performance satisfies the required specification of WLAN standard.

• 천문학회지
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• 제41권3호
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• pp.77-81
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• 2008

As a continuation of a previous work by Park et al. (2006), we have developed a two-element radio interferometer that can measure both the phase and amplitude of a visibility function. Two small radio telescopes with diameters of 2.3 m are used as before, but this time an external reference oscillator is shared by the two telescopes so that the local oscillator frequencies are identical. We do not use a hardware correlator; instead we record signals from the two telescopes onto a PC and then perform software correlation. Complex visibilities are obtained toward the sun at ${\lambda}\;=\;21\;cm$, for 24 baselines with the use of the earth rotation and positional changes of one element, where the maximum baseline length projected onto UV plane is ${\sim}\;90{\lambda}$. As expected, the visibility amplitude decreases with the baseline length, while the phase is almost constant. The image obtained by the Fourier transformation of the visibility function nicely delineates the sun, which is barely resolved due to the limited baseline length. The experiment demonstrates that this system can be used as a "toy" interferometer at least for the education of (under)graduate students.

• ETRI Journal
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• 제19권4호
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• pp.402-413
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• 1997

A CMOS device which has an extended heavily-doped amorphous silicon source/drain layer on the field oxide and an amorphous silicon local interconnection (ASLI) layer in the self-aligned source/drain region has been studied. The ASLI layer has some important roles of the local interconnections from the extended source/drain to the bulk source/drain and the path of the dopant diffusion sources to the bulk. The junction depth and the area of the source/drain can be controlled easily by the ASLI layer thickness. The device in this paper not only has very small area of source/drain junctions, but has very shallow junction depths than those of the conventional CMOS device. An operating speed, however, is enhanced significantly compared with the conventional ones, because the junction capacitance of the source/drain is reduced remarkably due to the very small area of source/drain junctions. For a 71-stage unloaded CMOS ring oscillator, 128 ps/gate has been obtained at power supply voltage of 3.3V. Utilizing this proposed structure, a buried channel PMOS device for the deep submicron regime, known to be difficult to implement, can be fabricated easily.

• ETRI Journal
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• 제27권5호
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• pp.569-578
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• 2005

The purpose of this paper is to describe the implementation of monolithically matching circuits, interface circuits, and RF core circuits to the same substrate. We designed and fabricated on-chip 1 to 6 GHz up-conversion and 1 to 8 GHz down-conversion mixers using a 0.8 mm SiGe hetero-junction bipolar transistor (HBT) process technology. To fabricate a SiGe HBT, we used a reduced pressure chemical vapor deposition (RPCVD) system to grow a base epitaxial layer, and we adopted local oxidation of silicon (LOCOS) isolation to separate the device terminals. An up-conversion mixer was implemented on-chip using an intermediate frequency (IF) matching circuit, local oscillator (LO)/radio frequency (RF) wideband matching circuits, LO/IF input balun circuits, and an RF output balun circuit. The measured results of the fabricated up-conversion mixer show a positive power conversion gain from 1 to 6 GHz and a bandwidth of about 4.5 GHz. Also, the down-conversion mixer was implemented on-chip using LO/RF wideband matching circuits, LO/RF input balun circuits, and an IF output balun circuit. The measured results of the fabricated down-conversion mixer show a positive power conversion gain from 1 to 8 GHz and a bandwidth of about 4.5 GHz.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1062-1065
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• 2002

We demonstrate the MMIC(monolithic microwave integrated circuit) frequency doublers generating stable and low-cost 29 ㎓ local oscillator signals from 14.5 ㎓ input signals. These devices were designed and fabricated by using the MMIC integration process of 0.1 $\mu\textrm{m}$ gate-length PHEMTs (pseudomorphic high electron mobility transistors). The measurements showed S$\_$11/ of -9.2 dB at 14.5 ㎓, S/sub22/ of -18.6 dB at 29 ㎓ and a minimum conversion loss of 18.2 dB at 14.5 ㎓ with an input power of 6 dBm. The fundamental signal of 14.5㎓ was suppressed below 15.2 dBc compared with the second harmonic signal at the output port, and the isolation characteristics of the fundamental signal between the input and the output port were maintained above 30 dB in the frequency range of 10.5 ㎓ to 18.5 ㎓.