• JSTS:Journal of Semiconductor Technology and Science
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• 제16권5호
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• pp.675-681
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• 2016

A 41dB gain control range $6^{th}$-order band-pass receiver front-end (RFE) using CMOS switched frequency translated impedance (FTI) is presented in a 40 nm CMOS technology. The RFE consists of a frequency tunable RF band-pass filter (BPF), IQ gm cells, and IQ TIAs. The RF BPF has wide gain control range preserving constant filter Q and pass band flatness due to proposed pre-distortion scheme. Also, the RF filter using CMOS switches in FTI blocks shows low clock leakage to signal nodes, and results in low common mode noise and stable operation. The baseband IQ signals are generated by combining baseband Gm cells which receives 8-phase signal outputs down-converted at last stage of FTIs in the RF BPF. The measured results of the RFE show 36.4 dB gain and 6.3 dB NF at maximum gain mode. The pass-band IIP3 and out-band IIP3@20 MHz offset are -10 dBm and +12.6 dBm at maximum gain mode, and +14 dBm and +20.5 dBm at minimum gain mode, respectively. With a 1.2 V power supply, the current consumption of the overall RFE is 40 mA at 500 MHz carrier frequency.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.912-915
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• 2004

Inductors material utilized in the downsizing passive devices and Rf components requires the physical and electrical properties at given area such as inductors thickness reduction, inductance and q-factor increase, low leakage current and thermal stability. In this study, Spiral inductors on the $SiO_2/Si$(100) substrate were fabricated by the magnetron sputtering method. Cu thin film with the thickness of $2{\mu}m$ was deposited on the substrate. Also we fabricated square inductors through the wet chemical etching technique. The inductors are completely specified by the turn width and the spacing between spirals. Both the width and spacing between spirals were varied from 10 to $60{\mu}m$ and from 20 to $70{\mu}m$, respectively. Inductance and Q factor dependent on the RF frequency were investigated to analyze performance of inductor arrays

• 한국항공우주학회지
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• 제44권3호
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• pp.212-217
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• 2016

저궤도 위성용 S대역 수신기 EM 모델을 개발 하였다. 복조기는 복조 방식의 확장성을 고려하여 복조 기능을 FPGA를 사용하여 구현하였으며 제작된 수신기는 RF 단과 디지털 복조기 그리고 전원부로 구성되고 운용상 발생되는 주파수 편이 보상을 위한 도플러 추적 기능을 가진다. 측정결과 수신기의 BER은 -110dBm의 RF입력전력에서 $1.0{\times}10^{-6}$로 측정 되었으며, 중심 주파수를 기준으로 ${\pm}100KHz$의 주파수 추적기능을 가진다. 요구된 환경 온도 테스트를 완료하였으며, TID 테스트 결과 기준치인 10Krad를 만족한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
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• pp.141-144
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• 2003

This study proposes ZnO thin film as a piezoelectric material for SAW (surface acoustic wave) filter. The ZnO thin film with thickness $2.6{\mu}m$ was deposited (0001)-oriented sapphire by RF magnetron sputtering technique. IDTs (inter-digital transducers) electrodes were patterned upon SAW filter mask with solid finger structure unapodized using lift-off method on ZnO piezoelectric thin film. SAW propagation velocity was measured with the center frequency by HP 8753C network analyzer. A fabricated ZnO SAW filter exhibited a high propagation velocity of 5433 $^m/s$ and relatively insertion loss of -53.391dB at $\lambda=80{\mu}m$. The side-lobe attenuation of the center frequency was about 17dB. When the wavelength was $80{\mu}m$ $(\lambda/4=20{\mu}m)$, the center frequency was 67.907 MHz. $k^2$ (electromechanical coupling coefficient) was 15.84 %.

• 한국가구학회지
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• 제17권1호
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• pp.33-46
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• 2006

This study was carried out to investigate a radio-frequency/vacuum (RF/V) drying ability and physical properties of the green boards and the pre-kiln dried boards with 40 mm thickness, and the 70 mm-thick green board of Iroko (Milicia excelsa). The major results were summarized as follows; The drying time from initial moisture content (MC) of 110% to approximate 6% MC for a 40mm-thick green board was 192 hours, and about 200 hours for the 70 mm-thick green board, respectively and so the RF/V drying times were dramatically shortened compared to conventional kiln drying time. The case hardenings at the RF/V drying completion stage test were very negligible, thus represented almost no existence of the residual stress. The checks were very slightly formed on all of the boards during the RF/V drying test, but crook appeared quite severely. During the accelerating test, the water-resistant treated specimens had not experienced any signs of checking occurred, whereas the control boards had encountered very frequent occurrences of end checking and slight surface checking. There were no observations of warping and discoloring regardless of the treatment.

• 정보보호학회논문지
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• 제17권1호
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• pp.89-96
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• 2007

EPC 네트워크(Electronic Product Code Network) 환경 기반의 REID 시스템은 사물에 직접적인 접촉을 하지 않고 RF(Radio Frequency)신호를 이용하여 사물의 정보를 읽어 오거나 기록할 수 있다. 이것은 기존의 바코드 시스템에 비해서 저장능력이 뛰어나며 비접촉식이라는 이점을 갖는다. 이런 RFID 시스템과 모바일 시스템을 접목함으로서 사용자에게 새로운 부가서비스를 제공하는 모바일 REID 시스템이 만들어지게 되었다. 그러나 비접촉식의 RF(Radio Frequency) 통신을 이용하여 사물의 정보를 가져온다는 이점은 개인의 프라이버시 침해라는 문제점을 발생시킨다. 본 논문에서는 모바일 기반의 RFID 시스템에서의 개인 프라이버시를 보호하는 기법을 제안한다. 제안한 기법은 기존에 제안된 기법들 보다 효율적으로 프라이버시 보호기능을 제공한다.

• 한국전자파학회논문지
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• 제29권11호
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• pp.821-827
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• 2018

골다공증을 치료하기 위하여 조골세포의 재형성 증가를 위해 사용되는 장치에서는 뼈의 외부에서 자기장을 인가하게 되면 뼈에 포함된 무기질이 일정한 방향으로 정렬되며, 세차운동을 하게 된다. 이러한 상황에서 RF 코일을 이용하여 90도 RF 펄스를 인가하면 무기질의 양성자가 여기 상태에 이르게 되며, 뼈 속에서의 조골세포의 침착에 촉진하는 인의 활성도가 증가하여 뼈의 재형성이 증가하게 된다. 이 때 세차 운동 주파수의 고조파에 해당하는 신호를 RF 코일에서 90도 RF 펄스로 발생시키는 RF 코일의 크기를 소형화하면 조골세포 재형성 시스템의 전체 크기를 획기적으로 감소시킬 수 있다. 본 연구에서는 조골세포 재형성 시스템에 사용될 수 있는 RF 코일의 소형화를 위한 방법론을 제시하며, 설계 후 측정을 통하여 검증한다. 본 연구에서 구현한 RF 코일의 커패시터는 25 pF, 인덕터는 약 100 nH, 공진주파수는 대략 96 MHz이며, 제작된 RF 코일의 end 링의 반지름은 18 cm, 다리 총 길이는 $2{\times}11.6cm$이다.

• 한국광학회지
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• 제15권3호
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• pp.274-277
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• 2004

본 논문에서는 두 개의 중첩된 Mach-Zehnder 구조의 변조기를 이용한 집적광학형 RF 위상변환기를 제안하고, 새로운 전기광학폴리머를 이용하여 제작하였다. 구현된 소자는 RF신호의 위상을 전압에 의하여 연속적으로 제어할 수 있는 특징을 갖는다. 본 논문에서는 16 GHz RF신호의 경우에 대해, 7.8 $V_{pp}$ 제어 전압을 인가하여 약 108$^{\circ}$범위에서 RF신호의 위상을 거의 선형적으로 변환시킬 수 있었다.다.

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

• ETRI Journal
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• 제32권4호
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• pp.503-511
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• 2010

WiBro radio frequency (RF) repeater is used for solving the problem of partial shadow areas in the wireless communication field that uses time-division duplexing (TDD) mode. In this paper, a method to efficiently generate TDD signals for WiBro RF repeater is proposed and its digital circuit is implemented. A TDD signal is detected from RF signals transmitted/received to/from RF repeater and then inputted again into the RF repeater, so that it can operate normally. First, the envelope of downlink signals is detected and then clamped to extract the basic form of a TDD signal using an operational amplifier circuit. Next, the TDD signal is generated by restoring and filtering the shape which has been distorted by the wireless channel. The algorithm and system to acquire TDD signal are developed with a goal to have simple but powerful functions with as little cost as possible. The proposed method is implemented as an RF-digital integrated system and verified through the experiments under the same condition as actual WiBro service environment.