• Proceedings of the IEEK Conference
• /
• 2002.06a
• /
• pp.167-170
• /
• 2002

The design and fabrication of Q-band 3-stage monolithic microwave integrated circuit(MMIC) driver and power amplifiers for WLAN are presented using 0.2${\mu}{\textrm}{m}$ AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor(PHEMT). In each stage of the MMIC DA, a negative feedback is used for both broadband and good stability. The MMIC PA has employed a balanced configuration to overcome these difficulties and achieve high power with low VSWR over a wide frequency range. In the MMIC DA, the measurement results arc achieved as an input return loss under -4dB, an output return loss under -l0dB, a gain of 14dB, and a PldB of 17dB at C-band(36~ 44GHz). The chip size is 28mm$\times$1.3mm. The developed MMIC PA has the l0dB linear gain over 360Hz to 420Hz band and 22dBm PldB performance at 400Hz. The size of fabricated MMIC PA is 4mm x3mm. These results closely match with design results. This MMIC DA Sl PA will be used as the unit cells to develop millimeter-wave transmitters for use in wideband wireless LAN systems.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.1
• /
• pp.57-62
• /
• 1999

Polycrystaline thin film transistors are fabricated on the transparent glass substrate by a lamp-scan annealing. The line-shaped lamp scanning method, which is profitable for large area process, effectively radiated silicon film on glass substrate. Amorphous silion film absorbs the light which is emitted from halogen-lamp and it transformed into crystalline silicon by metal-induced lateral crystallization. In order to enhance the annealing effect, capping layer was deposited on the whole substrate. When the scan speed was 1-2mm/sec, lateral crystallization of amorphous silicon under capping layer was 18~27${\mu}m/scan$. The thin film transistor fabricated by this method shows high electron mobility over 130$cm^2/V{\cdot}sec$

• ETRI Journal
• /
• v.36 no.2
• /
• pp.206-213
• /
• 2014

This paper presents a novel 90 GHz band 16-quadrature amplitude modulation (16-QAM) orthogonal frequency-division multiplexing (OFDM) communication system. The system can deliver 6 Gbps through six channels with a bandwidth of 3 GHz. Each channel occupies 500 MHz and delivers 1 Gbps using 16-QAM OFDM. To implement the system, a low-noise amplifier and an RF up/down conversion fourth-harmonically pumped mixer are implemented using a $0.1-{\mu}m$ gallium arsenide pseudomorphic high-electron-mobility transistor process. A polarization-division duplex architecture is used for full-duplex communication. In a digital modem, OFDM with 256-point fast Fourier transform and (255, 239) Reed-Solomon forward error correction codecs are used. The modem can compensate for a carrier-frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of $10^{-5}$ at a signal-to-noise ratio of about 19.8 dB.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.11 no.12
• /
• pp.1159-1164
• /
• 2016

This study describes the design and implementation of SHF band Low Noise Amplifier of Digital Satellite Communication. We have applied to HEMT part to minimize Noise Figure of system. and minimized the potential for the occurrence of such erroneous operation of equipment through the simulations of the space environment. We designed a reliable Low Noise Amplifier through simulation for a TID according to the vibration generated during the launch and space radiation environment, and compared pre-simulation of main performance results to test results about main performances of Low Noise Amplifier after production.

• ETRI Journal
• /
• v.27 no.2
• /
• pp.133-139
• /
• 2005

A monolithic microwave integrated circuit (MMIC) chip set consisting of a power amplifier, a driver amplifier, and a frequency doubler has been developed for automotive radar systems at 77 GHz. The chip set was fabricated using a 0.15 ${\mu}$ gate-length InGaAs/InAlAs/GaAs metamorphic high electron mobility transistor (mHEMT) process based on a 4-inch substrate. The power amplifier demonstrated a measured small signal gain of over 20 dB from 76 to 77 GHz with 15.5 dBm output power. The chip size is 2mm${\times}$ 2mm. The driver amplifier exhibited a gain of 23 dB over a 76 to 77 GHz band with an output power of 13 dBm. The chip size is 2.1mm${\times}$ 2mm. The frequency doubler achieved an output power of -6 dBm at 76.5 GHz with a conversion gain of -16 dB for an input power of 10 dBm and a 38.25 GHz input frequency. The chip size is 1.2mm ${\times}$ 1.2mm. This MMIC chip set is suitable for the 77 GHz automotive radar systems and related applications in a W-band.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.28A no.11
• /
• pp.902-909
• /
• 1991

A reproducible selective dry etch process of GaAs/AlGaAs Heterostructures for High Electron Mobility Transistor(HEMT) Device fabrication is developed. Using RIE mode with $CCl_{2}F_{2}$ as the basic process gas, the observed etch selectivity of GaAs layer with respect to GaAs/$Al_{0.3}Ga_{0.7}$As is about 610:1. Severe polymer deposition problem, parialy generated from the use of $CCl_{2}F_{2}$ gas only, has been significantly reduced by adding a small amount of He gas or by $O_{2}$ plasma ashing after etch process. In order to obtain an optimized etch process for HEMT device fabrication, we com pared the properties of the wet etched Schottky contact with those of the dry etched one, and set dry etch condition to approach the characteristics of Schottky diode on wet etched surface. By applying the optimized etch process, the fabricated HEMT devices have the maximum transconductance $g_{mext}$ of 224 mS/mm, and have relatively uniform distribution across the 2inch wafer in the value of 200$\pm$20mS/mm.

• Proceedings of the IEEK Conference
• /
• 2002.07b
• /
• pp.1054-1057
• /
• 2002

The design and fabrication of Q-band 3-stage monolithic microwave integrated circuit(MMIC) amplifier for WLAN are presented using 0.2$\square$ AIGaAs/lnGaAs/GaAs pseudomorphic high electron mobility transistor (PHEMT). In each stage of the MMIC, a negative feedback is used for both broadband and good stability. The measurement results are achieved as an input return loss under -4dB, an output return loss under -10dB, a gain of 14dB, and a PldB of 17dBm at Q-band(36～44GHz). These results closely match with design results. The chip size is 2.8${\times}$1.3mm$^2$. This MMIC amplifier will be used as the unit cell to develop millimeter-wave transmitters for use in wideband wireless LAN systems.

• ETRI Journal
• /
• v.34 no.5
• /
• pp.649-654
• /
• 2012

This paper presents a novel 16-quadrature-amplitude-modulation (QAM) E-band communication system. The system can deliver 10 Gbps through eight channels with a bandwidth of 5 GHz (71-76 GHz/81-86 GHz). Each channel occupies 390 MHz and delivers 1.25 Gbps using a 16-QAM. Thus, this system can achieve a bandwidth efficiency of 3.2 bit/s/Hz. To implement the system, a driver amplifier and an RF up-/down-conversion mixer are implemented using a $0.1{\mu}m$ gallium arsenide pseudomorphic high-electron-mobility transistor (GaAs pHEMT) process. A single-IF architecture is chosen for the RF receiver. In the digital modem, 24 square root raised cosine filters and four (255, 239) Reed-Solomon forward error correction codecs are used in parallel. The modem can compensate for a carrier-frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of $10^{-5}$ at a signal-to-noise ratio of about 21.5 dB.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2001.11a
• /
• pp.213-217
• /
• 2001

본 논문에서는 CPW 구조를 이용하여 60 GHz 무선 시스템 응용을 위한 V-band용 하향 주파수 혼합기를 설계 및 제작하였다. 하향 주파수 혼합기의 설계 및 제작에 있어서 GaAs PHEMT(Pseudomorphic high electron mobility transistor)를 기반으로 하였으며, 회로설계를 위해 coplanar waveguide(CPW) 라이브러리를 구축하여 이용하였다. 제작된 하향 주파수 혼합기의 변환이득은 국부발진주파수(LO) 입력이 8 dBm일 때 -8.5 dB의 최대 변환이득 특성을 얻었으며 Pl dB는 -3.3 dBm을 얻었다. 제작된 회로의 칩 크기는 1.6$\times$l.6 $\textrm{mm}^2$ 이다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.561-561
• /
• 2012

Graphene, two dimensional single layer of carbon atoms, has tremendous attention due to its superior property such as fast electron mobility, high thermal conductivity and optical transparency, and also found many applications such as field-effect transistors (FET), energy storage and conversion, optoelectronic device, electromechanical resonators and chemical sensors. Several techniques have been developed to form the graphene. Especially chemical vapor deposition (CVD) is a promising process for the large area graphene. For the electrically isolated devices, the graphene should be transfer to insulated substrate from Cu or Ni. However, transferred graphene has serious drawback due to remaining polymeric residue during transfer process which induces the poor device characteristics by impurity scattering and it interrupts the surface functionalization for the sensor application. In this study, we demonstrate the characteristics of solution-gated FET depending on the removal of polymeric residues. The solution-gated FET is operated by the modulation of the channel conductance by applying a gate potential from a reference electrode via the electrolyte, and it can be used as a chemical sensor. The removal process was achieved by several solvents during the transfer of CVD graphene from a copper foil to a substrate and additional annealing process with H2/Ar environments was carried out. We compare the properties of graphene by Raman spectroscopy, atomic force microscopy(AFM), and X-ray Photoelectron Spectroscopy (XPS) measurements. Effects of residual polymeric materials on the device performance of graphene FET will be discussed in detail.