• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.197-201
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• 2000

In this paper, a MMIC(Monolithic Microwave Integrated Circuit) broadband drive amplifier for wireless communication system has designed using active feedback method. The MMIC brodband amplifier was designed using 0.5$\mu\textrm{m}$ MESFET of ETRI library. Simulation results show that gain is 22 dB, and gain flatness ${\pm}$1 dB. Maximum output power 15 dBm and noise figure 2.5 dB in bandwidth 500 MHz ～3.0 GHz. The MMIC Broadband amplifer's chip area is 14mm${\times}$1.4mm.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.4
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• pp.274-280
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• 2007

This paper demonstrates an efficiency improvement of the class E power amplifier (PA) by tuning-out the input capacitance ($C_{IN}$) of the power HBT with a shunt inductance. In order to obtain high output power, the PA needs the large emitter size of a transistor. The larger the emitter size, the higher the parasitic capacitance. The parasitic $C_{IN}$ affects the distortion of the voltage signal at the base node and changes the duty cycle to decrease the PA's efficiency. Adopting the L-C resonance, we obtain a remarkable efficiency improvement of as much as 7%. This PA exhibits output power of 29 dBm and collector efficiency of 71% at 1.9 GHz.

• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.81-86
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• 2002

This paper presents the full wave analysis of microwave circuits with nonlinear device using the finite difference time domain method. The equivalent current source is used to model nonlinear device and all the electric field components at the nonlinear device are updated by FDTD algorithm. The currents and voltages of nonlinear device are calculated by the state equations and iteration method. To validate the proposed method, the S-parameters of NEC NE72089 MESFET in various conditions are analyzed and the results are compared with those of the ADS. The proposed method is applied to the analysis of a microwave amplifier, which includes NEC NE72089 MESFET. The analysis results obtained by the present method show good agreement with those of the ADS.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.154-158
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• 2005

In this paper, we design optical receiver composed of CDR(clock and data recovery), SA(sense amp), TIA(transimpe dence amplifier), and decision circuit. The optical receiver can be classified to two main block, one is Deserializer composed of CDR and SA, another is PD receiver composed of preamplifier(샴), peak detector, etc. In this paper, we propose CDR using delayed data topology that could improve defects of existing CDR. The optical receiver that is proposed in this paper has the role of translation a 1.25 Gb/s optical signal to $10{\times}125 Mb/s$ array electric signals. This optical receiver is verified by simulator(hspice) using 0.35 um CMOS technology.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.107-114
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• 2020

A power amplifier of 2.4 GHz ISM band is designed to implement a transmitter system. High efficiency amplifiers can be implemented as class E or class F amplifiers. This study has designed a 20 W high efficiency class E amplifier that has simple circuit structure in order to utilize for the ISM band application. The impedance matching circuit was designed by class E design theory and circuit simulation. The designed amplifier has the output power of 44.2 dBm and the power added efficiency of 69% at 2.45 GHz. In order to apply 30 dBm input power to the designed power amplifier, voltage controlled oscillator (VCO) and driving amplifier have been fabricated for the input feeding circuit. The measurement of the power amplifier shows 43.2 dBm output and 65% power added efficiency. This study can be applied to the design of power amplifiers for various wireless communication systems such as wireless power transfer, radio jamming device and high power transmitter.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.37-43
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• 2009

This paper describes a monolithic Darlington-cascade amplifier (DCA) operating at X-band, realized with a 0.35-micron SiGe bipolar process, which provides 45 GHz $f_T$. A conventional cascade amplifier was also designed on the same process and tested to establish a reference. Compared to the reference cascade amplifier, the proposed monolithic amplifier circuit exhibits an improved gain of 2.5 dB and improved output power 1-dB compression point of 5.2 dB with 72% wider bandwidth. Measurement results show 19.5 dB gain, 11.2 dBm 1-dB compression power, and 3.1 GHz bandwidth. These results demonstrate that the Darlington-cascade cell is an advantageous substitute to the conventional cascade amplifier.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.1
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• pp.19-26
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• 1987

The broadband microwave amplifier in the 3~4GHz frequency range has been designed by using potentially unstable GaAs FET. Input matching network is designed by 14dB available power gain circles which are in the stable region. In order to obtain maximu, transducer power gain, output matching network which is in the stable region can be designed using Fano's bandpass matching network. The measured values of transducer power gain, $S_11$and $S_22$ show close agreements with the theoretical valuse.

• Journal of electromagnetic engineering and science
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• v.16 no.1
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• pp.44-51
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• 2016

A commercial $0.25{\mu}m$ GaN process is used to implement 6-18 GHz wideband power amplifier (PA) monolithic microwave integrated circuits (MMICs). GaN HEMTs are advantageous for enhancing RF power due to high breakdown voltages. However, the large-signal models provided by the foundry service cannot guarantee model accuracy up to frequencies close to their maximum oscillation frequency ($F_{max}$). Generally, the optimum output load point of a PA varies severely according to frequency, which creates difficulties in generating watt-level output power through the octave bandwidth. This study overcomes these issues by the development of in-house large-signal models that include a thermal model and by applying distributed L-C output load matching to reactive matched amplifiers. The proposed GaN PAs have successfully accomplished output power over 5 W through the octave bandwidth.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.124-127
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• 2005

국내에서는 언제 어디서나 휴대용 단말을 이용하여 저렴한 요금으로 고속의 무선인터넷을 사용할 수 있는 휴대인터넷 서비스를 2006년부터 서비스 할 계획이다. 앞으로 서비스 될 WiBro 휴대인터넷 서비스 방식은 기존 이동통신 방식과 달리 RF 송신 주파수와 수신 주파수가 동일한 TDD (time division duplexing) 방식을 사용한다. WiBro 무선통신 기지국 장비에 있어서도 기존 CDMA 이동통신 기지국 장비에서와 마찬가지로 RF Power Amplifier (PA)가 매우 고가의 핵심 부품이라 할 수 있다. 물론, 기존 FDD (frequency division duplexing) 방식의 CDMA 기지국 PA와 달리 WiBro용 기지국 PA는 TDD 신호를 처리할 수 있는 새로운 기술을 필요로 한다. TDD 방식인 WiBro 기지국용으로 사용할 수 있는 새로운 2.3 GHz 42 W PA를 설계, 제작한 결과를 본 논문에서는 발표하고자 한다.

• Electronics and Telecommunications Trends
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• v.37 no.5
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• pp.11-21
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• 2022

GaN (Gallium-Nitride) is a promising candidate material in various radio frequency applications due to its inherent properties including wide bandgap, high carrier concentration, and high electron mobility/saturation velocity. Notably, AlGaN/GaN heterostructure field effect transistor exhibits high operating voltage and high power-density/power at high frequency. In next-generation radar systems, GaN power transistors and monolithic microwave integrated circuits (MMICs) are significant components of transmitting and receiving modules. In this paper, we introduce technological trends for C-/X-/Ku-band GaN MMICs including power amplifiers, low noise amplifiers and switch MMICs, focusing on the status of GaN MMIC fabrication technology and GaN foundry service. Additionally, we review the research for the localization of C-/X-/Ku-band GaN MMICs using in-house GaN transistor and MMIC fabrication technology. We also discuss the results of C-/X-/Ku-band GaN MMICs developed at Defense Materials and Components Convergence Research Department in ETRI.