• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.11
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• pp.79-85
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• 1995

In this paper, an epi layer and a device structure for InP/InGaAs p-i-n/HBT OEIC is designed for a receiving frontend of high speed optical communications. A 3 stage transimpedance circuit using the p-i-n/HBT device is also designed by SPICE simulations for a high sensitivity including ISI noises at a given bit rate. Our simulations show that the Personick's assumption which is not commonly satisfied have estimated a photoreceiver sensitivity too high, so thus we have to also consider ISI noises in OCIC receiver designs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.127-128
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• 2006

The proposed differential LC cross-coupled VCO is implemented in InGap/GaAs HBT process for an adaptive Global Positioning system(GPS) application. Two filtering capacitors are used at the base of output buffer amplifiers at the both sides of the core m order to improve phase noise characteristics. The VCO produced a phase noise of -133 dBc/Hz at 3MHz offset frequency from the carrier frequency of 1.489GHz and the second harmonic suppression is significantly suppresed up to -49dBc/Hz in simulation result. The three pairs of BC diodes are integrated m the tank circuit to increase the VCO Tunning range.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.245-248
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• 2000

In this paper, we present a high-performance SiGe HBT's RF input impedance parameter extraction method. The SiGe HBT has emitter width of 0.5${\mu}{\textrm}{m}$ and length of 6${\mu}{\textrm}{m}$. S-parameter has been measured with the collector current of 1~3㎃ using on-wafer RF measuring system . The pre-calculation method was used in order to overcome the local minimum problem. This method enabled us to extract a RF(1~10㎓) input impedance parameter.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.6
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• pp.777-783
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• 2007

In this work, a highly integrated downconverter MMIC employing HBT(heterojunction bipolar transistor) was developed for application to one chip tranceiver solution of Ku-band commercial wireless communication system. The downconverter MMIC (monolithic microwave integrated circuit) includes mixer filter. amplifier and input/output matching circuit. Especially, spiral inductor structures employing SiN film were used for a suppression of LO and its second harmonic leakage signals. Concretely, they were properly designed so that the self-resonance frequency was accurately tuned to LO and its second harmonic frequency, and they were integrated on the downconverter MMIC.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.7
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• pp.15-22
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• 1997

A 10Gbit/s limiting amplifier IC for optical transmission system was implemented with AlGaAs HBT (heterojunction bipolar transistor) technology. HBTs with 2x10.mu. $m^{2}$ and 6x20.mu. $m^{2}$ emitter size were used. The HBT structures are based on metal-organic chemical vapor deposition (MOCVD) epitxy and employ a mesa structure with self-aligned emitter/base and sidewall dielectric passivation. IC was designed to support differnetial input and output. Small signal performance of the packaged IC showed 26dB gain and $f_{3dB}$ of 8GHz. A single ouput has 800m $V_{p-p}$ swing with more than 26dB dynamic range. The performance of the limiting amplifier was verified through single mode fiber320km transmission link test.est.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.257-261
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• 2001

This paper presents the implementation of wide-band RFIC amplifier operating from near 50MHz to 3GHz using Tachyonics SiGe HBT foundry. Voltage shunt feedback is used for the flat gain and the broad band impedance matching. Initial design parameters are calculated using the low frequency small signal analysis. Since the HBT model was not available at the design time, discrete tuning board was made for fine tuning in the low frequency range. Fabricated amplifier shows 12dB gain with 1dB fluctuation and PldB reaches 15dBm at 850MHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.201-208
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• 2000

In the transmitter of optical communication systems, a time-division multiplexer combines several parallel data streams into a single data stream with a high bit rate. In this paper, we design a 4:1 (4-channels) time-division multiplexer using SiGe HBT with emitter size of 2x8um2. The operation speed is 100bps, the rise and fall times of 20-80% are 34ps and 34ps, respectively and the dissipation of power is 1.50W.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.26-28
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• 1996

A high power SiGe HBT has been fabricated using APCVD(Atmospheric Pressure Chemical Vapor Deposition) and its perfermanoe has been analysed. The composition of Ge in the SiGe base was graded from 0% at the emitter-base junction to 20% at the base-collector junction. As a base electrode, titanium disilicide(TiSi$_2$) was used to reduce the extrinsic base resistance. The SiGe HBT with an emitter area of 2$\times$8${\mu}{\textrm}{m}$$^2$typically has a cutoff frequency(f$_{T}$) of 7.0GHz and a maximun oscillation frequency(f$_{max}$) of 16.1GHz with a pad de-embedding. The packaged high power SiGe HBT with an emitter area of 2xBx80${\mu}{\textrm}{m}$$^2$typically shows a cutoff frequency of 4.7GHz and a maximun oscillation frequency of 7.1GHz at Ic of 115mA.A.A.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.29-32
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• 1996

AlGaAs/GaAs 에피 구조와 제조 공정에 사용될 마스크를 설계 및 제작하여, 이를 이용하여 다양한 크기의 HBT를 제작하였다. 제작될 소자의 특성에 영향 을 미치는 공정에 대해서는 단위 공정을 수행하여 발생될 수 있는 문제점들을 사전에 제거하고, 안정된 공정 조건을 확립하도록 하였다. 금속의 저항성 접촉특성 향상을 위한 단위 실험 결과, n형 및 p형 금속에 대하여 각각 3.5$\times$$10^{-6}$-$ extrm{cm}^2$와 1.0$\times$$10^{-5}$$\Omega$-$\textrm{cm}^2$의 접촉 비저항 특성을 얻었다. 또한, 제작된 HBT는 HP4145B 와 HP8510C의 장비를 이용하여 DC 및 AC 특성을 측정하였는데, 에미터 크기가 3$\times$10um$^2$인 소자의 경우, $\beta$=51, f$_{T}$= 42GHZ 및 f$_{max}$=19GHz의 특성을 얻었다.

• Journal of the Korea Society of Computer and Information
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• v.5 no.4
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• pp.102-105
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• 2000

The self-aligned AICaAs/GaAs HBTs with the mesa-etched emitter showed severe degradation in current gain under stress. The cause was identified to be due to instability of the surface states on extrinsic base. In this paper the surface states were diminished by the hetero-passivation of the InGaP ledge emitter and the reliability was drastically improved. The activation energy of current gain degradation was extracted to be 1.97eV and MTTF to be 4.8$\times$108 at 14$0^{\circ}C$ which has satisfied MIL standards.