• 한국전기전자재료학회논문지
• /
• 제16권12호
• /
• pp.1077-1079
• /
• 2003

This paper describes the development of bulk acoustic wave (BAW) resonators using a PolyVinyliDene Fluoride (PVDF). The resonators have an air gap between a substrate for acoustic isolation without surface micromachining. We measured the resonance frequency and the input reflection coefficient (S$\sub$11/) of resonators using vector network analyzer. The fundamental resonance in this experimental result was measured at 1.4 ㎓ with a return loss of -23.2 ㏈. We can confirm a possibility of resonator application as using a PVDF because it can fabricate the resonator without etching process.

• International journal of advanced smart convergence
• /
• 제1권1호
• /
• pp.1-5
• /
• 2012

We propose a structure for a multiple input multiple output antenna which has no space for isolation. The antenna operates in a frequency range of 2.4-2.48 GHz and can achieve a high channel capability as a Bluetooth antenna. The MIMO antenna consists of two planar inverted F antennas with symmetric structure. We designed the proposed antenna using HFSS simulator, and we designed the fabricated antenna using PCB fabricator. The MIMO antenna's isolation $S_{21}{\leq}-10dB$ and reflection coefficient $S_{11}{\leq}-20dB$. The proposed antenna's specification satisfies Bluetooth antenna's criteria and has more space than the existing MIMO antennas, which have space for isolation.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제15권6호
• /
• pp.629-633
• /
• 2015

An active balun using current steering for phase correction is presented. The proposed active balun is constructed with two different unit balun structures based on current steering to reduce phase and amplitude errors. This type of topology can be compared with the conventional phase and amplitude correction techniques which do not incorporate the current steering. Designed and fabricated active balun in $0.18{\mu}m$ CMOS process operates over 0.95 - 1.45 GHz band, showing input reflection coefficient under -15 dB, phase error of $11^{\circ}$ and gain error of 0.5 dB. Gain is measured to be 0.3 dB maximum and power consumption of 7.2 mW is measured.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
• /
• pp.487-488
• /
• 1995

Broadband Microwave Low Noise Amplifier(LNA) is designed. The matching method using the broadband BPF(BandPass Filter) is introduced in this paper. This method is that the filter having the same reflection coefficient of Microwave GaAs FET in the desired bandwidth is located on the input stage of FET. The Simulated results is obtained that the $S_{21}$ and noise figure in 2.5GHz$\sim$9GHz, band are 8.5dB $\pm$ 1.5dB, 2.5dB $\pm$ 0.3dB respectively.

• Journal of information and communication convergence engineering
• /
• 제6권2호
• /
• pp.154-157
• /
• 2008

A class-E RF(Radio Frequency) power amplifier for wireless application is designed using standard CMOS technology. To drive the class-E power amplifier, a class-F RF power amplifier is used and the reliability characteristics are studied with a class-E load network. The reliability characteristic is improved when a finite-DC feed inductor is used instead of an RF choke with the load. After one year of operating, when the load is an RF choke the output current and voltage of the power amplifier decrease about 17% compared to initial values. But when the load is a finite DC-feed inductor the output current and voltage decrease 9.7%. The S-parameter such as input reflection coefficient(S11) and the forward transmission scattering parameter(S21) is simulated with the stress time. In a finite DC-feed inductor the characteristics of S-parameter are changed slightly compared to an RF-choke inductor. From the simulation results, the class-E power amplifier with a finite DC-feed inductor shows superior reliability characteristics compared to power amplifier using an RF choke.

• Journal of electromagnetic engineering and science
• /
• 제11권3호
• /
• pp.227-233
• /
• 2011

This paper describes the development of a broadband quasi-Yagi antenna using a folded dipole driver. The antenna is designed on a low-permittivity substrate to reduce the surface wave effect, and hence the gain can be enhanced easily by adding directors. The folded dipole driver is connected to a 50-${\Omega}$ microstripline via a simple broadband microstrip-to-coplanar stripline transition with a quarter radial stub. The key motivation for the use of a folded dipole is to increase the input impedance at the driver, allowing a smaller mismatch loss between the antenna driver and the coplanar stripline feed. The proposed antenna has a measured bandwidth of 4.67~6.26 GHz for the -10 dB reflection coefficient, and a flat gain of 4.86~5.15 dB within the bandwidth.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 하계학술대회 논문집 B
• /
• pp.509-512
• /
• 1995

The relaying algorithm to calculate the fault distance from only transient signal at faults in T/L is presented. In this paper. At faults the oscillation frequency components exist in both voltage and current and these components minimize the input impedance shown in fault point. The equivalent source impedance shown in relaying point is needed to calculate the fault distance using these components. To source impedance, the reflection coefficient between forward wave and backward and the Prony's analysis is also employed to extract the oscillation frequency component from transient signals. The case study show that the new distance relaying algorithm satisfies the high operation speed and high accuracy even if the algorithm uses only transient signals.

• Journal of information and communication convergence engineering
• /
• 제16권4호
• /
• pp.203-212
• /
• 2018

In this article, a novel design of patch antenna with wide band characteristics is presented. The proposed antenna is having electrical dimensions of $0.14{\lambda}{\times}0.11{\lambda}$ (at lower initial frequency) and footprints of $150mm^2$. Structural parameters optimization shows 3.1-23.5 GHz frequency range for a (reflection coefficient) $S_{11}{\leq}-10dB$ and simulated gain 6.8 dB is obtained. An equivalent circuit model is proposed to get an insight view of antenna. Advanced Systems Design (ADS) simulation results are obtain which confirm the validity of proposed model. Degenerated foster canonical form has been used to explain the reactance and capacitive behavior idea of simulated proposed antenna's input impedance later on an equivalent circuit model and smith chart is also suggested. HFSS and CST have been used to analyze antenna behavior. The proposed antenna can be further used for microwave image detection applications.

• 한국인터넷방송통신학회논문지
• /
• 제18권1호
• /
• pp.43-46
• /
• 2018

본 논문은 향상된 성능을 가진 개선 된 헤어핀 커플 링 구조인 스텝 임피던스 공진기 (SIR : Stepped Impedance Resonator)를 이용한 광대역 대역저지 여파기 (WBSF : Wide Band Stop Filter)를 설계하였다. SIR WBSF는 크기가 작고 탁월한 대역저지 특성을 갖는 장점이 있다. 설계된 BSF는 ${\lambda}/4$길이의 사각 모양의 헤어핀형을 입력과 출력 전송 라인 상측과 하측에 배치하여 대칭형이 되도록한 구조이다. 입출력 단자는시스템 응용을 위해 50 ohm으로 종단 되었다. SIR WBSF의 중심 주파수는 3.15 GHz의 제2 고조파 인 6.3 GHz이다. 설계된 여파기의 3dB 대역폭은 2.9 GHz이고 전송계수 ($S_{21}$)는 33.2 dB이다. 중심 주파수에서 반사계수 ($S_{11}$)은 0.106 dB이다. 응용분야는 육상고정 마이크로웨이브 중계국, 고정된 위성과 지구국, 고정 위성간 통신에 사용된다. 전체 크기는 $20mm{\times}10mm$이다.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2000년도 추계종합학술대회
• /
• pp.190-195
• /
• 2000

본 논문에서는 IMT-2000(International Mobile Telecommunication-2000) 휴대용 단말기 수신 주파수인 2.13 - 2.16 GHz 대역의 저잡음 중폭기(LNA ; Low Noise Amplifier)를 직렬 피드백과 저항결합 회로룰 이용하여 설계.구현하였다. 소스 리드에에 부가된 직렬 피드백은 중폭기의 저잡음 특성을 유지하면서 동시에 입력 반사계수를 작게 하고, 또한 대역내의 안정성을 향상시키는 역할을 하였다. 사용된 저항 결합회로는 저주파 영역의 신호를 정합 회로내의 저항을 통해 소모시킴으로써 저잡음 중폭기의 설계시 입력단 정함에 용이하였다. 저잡음 중폭기의 설계.제작에서 저잡음 증폭단에는 HP사의 GaAs FET인 ATF-10136을, 이득 증폭단에는 Mini-Circuit사의 내부 정합된 MMIC인 VNA-25를 사용하였다. 전원회로는 자기 바이어스(Self-bias) 회로를 사용하였고, 유전율 3.5인 테프론 기판 상에 장착하였다. 이렇게 제작된 저잡음 증폭기는 대역 내에서 30 dB 이상의 이득과 0.7 dB 이하의 잡음지수, $P_{ldB}$ 17 dB 이상, 그리고 입.출력 정재파비가 1.5 이하인 특성을 나타내었다.다.