• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.42 no.6
• /
• pp.23-36
• /
• 2005

PLLs have been widely used for many applications including communication systems. This paper presents a VCO with an improved negative skewed delay scheme and a PLL using this VCO. The proposed VCO and PLL are intended for replacing traditional LC oscillators and PLLs used in communication systems and other applications. The circuit designs of the VCO and PLL are based on 0.18um CMOS technology with 1.8V supply voltage. The proposed VCO employs subfeedback loops using pass-transistors and needs two opposite control voltages for the pass transistors. The subfeedback loops speed up oscillation depending on the control voltages and thus provide a high oscillation frequency. The two voltage controls have opposite frequency gain characteristics and result in low phase-noise. The 7-stage VCO in 0.18um CMOS technology operates from $3.2GHz\~6.3GHz$ with phase noise of about -128.8 dBc/Hz at 1MHz frequency onset. For 1.8V supply voltage, the current consumption is about 3.8mA. The proposed PLL has dual loop-filters for the proposed VCO. The PLL is operated at 5GHz with 1.8V supply voltage. These results indicate that the proposed VCO can be used for radio frequency operations replacing LC oscillators. The circuits have been designed and simulated using 0.18um TSMC library.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.7
• /
• pp.1639-1645
• /
• 2015

In UHD high-speed video transmission system, when a signal within certain frequency region coincides electrically and structurally, the system becomes unstable because the energy is concentrated, and signal flux is interfered and distorted. For the instability, power integrity analysis should be conducted. To remove the signal distortion for MLB, using a high-frequency design technique for EMI phenomenon, EMI which radiates electromagnetic energy fluxed into power layer was analyzed considering system stabilization. In this paper, we proposed an adaptive MLB design method which minimizes high-frequency noise in MLB structure, enhances signal integrity and power integrity, and suppresses EMI. The characteristic impedance for multi-layer circuit board proposed in this study were High-Speed Video Differential Signaling(HSVDS) line width w = 0.203, line gap d = 0.203, beta layer height h = 0.145, line thickness t = 0.0175, dielectric constant ε_r = 4.3, and characteristic impedance Zdiff = 100.186Ω. When high-speed video differential signal interface board was tested with optimized parameters, the magnitude of Eye diagram output was 672mV, jittering was 6.593ps, transmission frequency was 1.322GHz, signal to noise was 29.62dB showing transmission quality improvement of 10dB compared to previous system.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.1
• /
• pp.144-152
• /
• 2009

This paper propose highly miniaturized active $90^{\circ}C$ phase difference power divider and combiner for application to wireless communication system. The conventional passive $90^{\circ}C$ power divider and combiner cannot be integrated on MMIC because of their very large circuit size. Therefore, the highly miniaturized active $90^{\circ}C$ phase difference power divider and combiner are required for a development of highly integrated MMIC. In this paper, the highly miniaturized active $90^{\circ}C$ phase difference power divider and combiner employing InGaAs/GaAs HBT were designed, fabricated on GaAs substrate. According to the results, the circuit size of fabricated active $90^{\circ}C$ phase difference power divider and combiner were $1.67{\times}0.87$ mm and $2.42{\times}1.05$ mm, respectively, which were 31.6% and 2.2% of the size of conventional passive branch-line coupler. The output gain division characteristic of proposed divider circuit showed 8.4 dB and 7.9 dB respectively, and output phase difference characteristic showed $-89.3^{\circ}C$. The output gain coupling characteristic of proposed combiner circuit showed 9.4 dB and 10.5 dB respectively, and output phase difference characteristic showed $-92.6^{\circ}C$. The highly miniaturized active $90^{\circ}C$ phase difference power divider and combiner exhibited good RF performances compared with the conventional passive branch-line coupler.

• Journal of the Korean Vacuum Society
• /
• v.16 no.6
• /
• pp.439-445
• /
• 2007

SiGe integrated circuits are being used in the field of high-speed wire/wireless communications and microwave systems due to the RF/high-speed analog characteristics and the easiness in the fabrication. Reducing the resistance variation in SiGe thin film resistors results in enhancing the reliability of integrated circuits. In this paper, we investigate the causes that generate the resistance nonuniformity after the silicon-based thin film resistor was fabricated, and consider the counter plan against that. Because the Ti-B precipitate, which formed during the silicide process of the SiGe thin film resistor, gives rise to the nonuniformity of SiGe resistors, the boron ions should be implanted as many as possible. In addition, the resistance deviation increases as the size of the contact hole that interconnects the SiGe resistor and the metal line decreases. Therefore, the size of the contact hole must be enlarged in order to reduce the resistance deviation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.1
• /
• pp.384-389
• /
• 2011

This article presents an ultra broadband resistive power divider circuit for smart grid applications. Since the future smart grid system is expected to deploy high speed power line communication, the frequency response of the resitive power divider circuit is naturally of significance. Employing a thin film technology, the resistive power divider was designed, measured, and fabricated. For the circuit design, the conductor-backed coplanar waveguide line was firstly designed and measured. The 3 dB cutoff frequency was 72 GHz and S11 remains <-20 dB upto 70 GHz. The fabricated resistive power divider shows the 3 dB cutoff frequency of 50 GHz. It was experimentally verified that the resistive power divider circuit shows the insertion loss of 6 dB for high-speed input signal (40 Gb/s).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.3
• /
• pp.271-277
• /
• 2004

A Si(Silicon) MEMS(Micro Electro Mechanical System) package using a doped lossy Si carrier for CPW(Coplanar Waveguide) MMICs(Microwave and Millimeter-wave Integrated Circuits) is proposed in order to reduce parasitic problems of leakage, coupling and resonance. The proposed chip-carrier scheme is verified by fabricating and measuring a GaAs CPW on the two types of carriers(conductor-back metal, doped lossy Si) in the frequency from 0.5 to 40 ㎓. The proposed MEMS package using the lightly doped lossy(15 Ω$.$cm) Si chip-carrier and the HRS(High Resistivity Silicon, 15 ㏀$.$cm) shows the optimized loss and parasitic problems-free since the doped lossy Si-carrier effectively absorbs and suppresses the resonant leakage. The Si MEMS package for CPW MMICs has an insertion loss of only - 2.0 ㏈ and a power loss of - 7.5 ㏈ at 40 ㎓.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.9 no.1
• /
• pp.25-33
• /
• 1998

In this paper, we describe a single-gate MESFET mixer at PCS(Personal Communication Service) frequency band. The PCS frequency band is 1965~2025 MHz in FR and 140 MHz in IF irrespectly. The design of the mixer was executed by microwave simulator, EEsof Libra. The matching network is consisted of rectangular inductor, MIM capacitor and open stub. The ma- nufacture work was accomplished by the micro-pen and wedge-bonder. The mixer showed $6.69\pm0.65$ dB of conversion gain, $-14.9\pm3.5$dB of RF reflection coefficient and 57.83 dB of LO/IF isolation at 10 dBm of LO power when LO frequency is 1855 MHz. When this mixer is used at PCS terminal, IF-amplifier which compensates the conversion loss of diode mixer may be omitted.

• Journal of Advanced Navigation Technology
• /
• v.26 no.5
• /
• pp.358-364
• /
• 2022

The Inter Communication System for avionics is in charge of processing all voice signals that internal calls between Pilot and Co-pilot, internal calls between Pilots and Crews, external calls through communication equipment such as Ultra/Very High Frequency Receiver/Transmitter(U/VHF RT), audio signal monitoring for navigation and mission equipment such as VHF Omnidirectional Range/Instrument Landing System(VOR/ILS), Tactical Air Navigation(TACAN), audio signal output for voice recording to Flight Data Recorder(FDR) and Data Transfer System(DTS), and warning/caution audio signal generate about the status and threat of aircraft. Because Inter Communication System for avionics is sensitive to noise in the case of analog audio signals, a redundant design that can protect audio signal from electromagnetic noise inside/outside of aircraft is required for the mission of pilots and crews. In this paper, Normal/Back-up operation mode and redundancy design plan based on digital method for the redundancy of the digital Inter Communication System for avionics and manufacturing, verification results are described.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.162-162
• /
• 1999

초고주파 집적회로의 핵심소자로 각광을 받고 있는 GaAs MESFET(MEtal-emiconductor)은 게이트 형성 공정이 가장 중요하며, WNx 내화금속을 이용한 planar 게이트 구조의 경우 임계전압(Vth:threshold voltage)의 균일도가 우수할 뿐만 아니라 특히 Side-wall을 이용한 self-align 게이트는 소오스 저항을 줄일 수 있어 고성능의 소자 제작을 가능하게 한다.(1) 본 연구의 핵심이 되는 Side-wall을 형성하기 위하여 PECVD법에 의한 SiOx 박막을 증착하고, 건식식각법을 이용하여 SiOx side-wall을 형성하였다. 이 공정을 이용하여 소오스 저항이 낮고 임계전압의 균일도가 우수한 고성능의 self-aligned gate MESFET을 제작하였다. 3inch GaAs 기판상에 이온주입법에 의한 채널 형성, d.c. 스퍼터링법에 의한 WNx 증착, PECVD법에 의한 SiOx 증착, MERIE(Magnetic Enhanced Reactive Ion Etcing)에 의한 Side-wall 형성, LDD(Lightly Doped Drain)와 N+ 이온주입, 그리고 RTA(Rapid Thermal Annealing)를 사용하여 활성화 공정을 수행하였다. 채널은 40keV, 4312/cm2로, LDD는 50keV, 8e12/cm2로 이온주입하였고, 4000A의 SiOx를 증착한 후 2500A의 Side-wall을 형성하였다. 옴익 접촉은 AuGe/Ni/Au 합금을 이용하였고, 소자의 최종 Passivation은 SiNx 박막을 이용하였다. 제작된 소자의 전기적 특성은 hp4145B parameter analyzer를 이용한 전압-전류 측정을 통하여 평가하였다. Side-wall 형성은 0.3$\mu\textrm{m}$ 이상의 패턴크기에서 수직으로 잘 형성되었고, 본 연궁에서는 게이트 길이가 0.5$\mu\textrm{m}$인 MESFET을 제작하였다. d.c. 특성 측정 결과 Vds=2.0V에서 임계전압은 -0.78V, 트랜스컨덕턴스는 354mS/mm, 그리고 포화전류는 171mA/mm로 평가되었다. 특히 본 연구에서 개발된 트랜지스터의 게이트 전압 변화에 따른 균일한 트랜스 컨덕턴스의 특성은 RF 소자로 사용할 때 마이크로 웨이브의 왜곡특성을 없애주기 때문에 균일한 신호의 전달을 가능하게 한다. 0.5$\mu\textrm{m}$$\times$100$\mu\textrm{m}$ 게이트 MESFET을 이용한 S-parameter 측정과 Curve fitting 으로부터 차단주파수 fT는 40GHz 이상으로 평가되었고, 특히 균일한 트랜스컨덕턴스의 경향과 함께 차단주파수 역시 게이트 바이어스, 즉 소오스-드레스인 전류의 변화에 따라 균일한 값을 보였다. 본 연구에서 개발된 Side-wall 공정은 게이트 길이가 0.3$\mu\textrm{m}$까지 작은 경우에도 사용가능하며, WNx self-align gate MEESFET은 낮은 소오스저항, 균일한 임계전압 특성, 그리고 높고 균일한 트랜스 컨덕턴스 특성으로 HHP(Hend-Held Phone) 및 PCS(Personal communication System)와 같은 이동 통신용 단말기의 MMICs(Monolithic Microwave Integrates Circuits)의 제작에 활용될 것으로 기대된다.

• Journal of Internet Computing and Services
• /
• v.25 no.1
• /
• pp.99-107
• /
• 2024

Along with economic growth and industrial development, there is an increasing demand for various electronic components and device production of semiconductor, SMT component, and electrical battery products. However, these products may contain foreign substances coming from manufacturing process such as iron, aluminum, plastic and so on, which could lead to serious problems or malfunctioning of the product, and fire on the electric vehicle. To solve these problems, it is necessary to determine whether there are foreign materials inside the product, and may tests have been done by means of non-destructive testing methodology such as ultrasound ot X-ray. Nevertheless, there are technical challenges and limitation in acquiring X-ray images and determining the presence of foreign materials. In particular Small-sized or low-density foreign materials may not be visible even when X-ray equipment is used, and noise can also make it difficult to detect foreign objects. Moreover, in order to meet the manufacturing speed requirement, the x-ray acquisition time should be reduced, which can result in the very low signal- to-noise ratio(SNR) lowering the foreign material detection accuracy. Therefore, in this paper, we propose a five-step approach to overcome the limitations of low resolution, which make it challenging to detect foreign substances. Firstly, global contrast of X-ray images are increased through histogram stretching methodology. Second, to strengthen the high frequency signal and local contrast, we applied local contrast enhancement technique. Third, to improve the edge clearness, Unsharp masking is applied to enhance edges, making objects more visible. Forth, the super-resolution method of the Residual Dense Block (RDB) is used for noise reduction and image enhancement. Last, the Yolov5 algorithm is employed to train and detect foreign objects after learning. Using the proposed method in this study, experimental results show an improvement of more than 10% in performance metrics such as precision compared to low-density images.