• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.1-6
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• 2011

In this paper, an 1.5Gbit/s wireless data transmission system using the carrier frequency of 300 GHz band was implemented. The RF front-end was composed of schottky diode sub-harmonic mixer, frequency tripler, and horn antennas for transmitter and receiver, respectively. The LO frequencies of sub-harmonic mixer are 150GHz for transmit chain and 156GHz for receive chain. The ASK(Amplitude Shift Keying) modulation was used in the transmitter and the envelope detection method was used in the heterodyne receiver. The conversion loss of sub-harmonic mixer and implementation system loss were measured to be 9.8dB and 1.2dB, respectively. The 1.5Gbit/s video signal with HD-SDI format was transmitted over wireless distance of 40cm without optical lens(4.2m with optical lens) and displayed on HDTV at the transmitted average output power of $20{\mu}W$.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1418-1419
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• 2011

차세대 전력 반도체인 고전압 GaN 쇼트키 장벽 다이오드의 역방향 특성을 개선하기 위해서 열 산화공정이 제안되었다. AlGaN/GaN 에피탁시 위에 쇼트키 장벽 다이오드 구조가 제작되었으며, 쇼트키 컨택은 증착 후 $450^{\circ}C$에서 산화되었다. 열 산화공정이 메사 측벽의 AlGaN 및 GaN 표면에 $AlO_x$ 및 $GaO_x$를 형성하여 표면으로 흐르는 누설전류를 억제한다. 표면 및 GaN 버퍼를 통한 누설전류는 열 산화 공정 이후 100 ${\mu}m$-너비당 51.3 nA에서 24.9 pA로 1/2000 배 수준으로 감소하였다. 표면 산화물 형성으로 인하여 생성된 Ga-vacancy와 Al-vacancy는 acceptor로 동작하여 surface band bending을 증가시켜 쇼트키 장벽 높이를 증가시킨다. 애노드-캐소드 간격이 5 ${\mu}m$인 제작된 소자는 0.99 eV의 높은 쇼트키 장벽 높이를 획득하여, -100 V에서 0.002 A/$cm^2$의 낮은 누설전류를 확보하였다. 애노드-캐소드 간격이 5에서 10, 20, 50 ${\mu}m$로 증가되면 소자의 항복전압은 348 V에서 396, 606, 941 V로 증가되었다. 열 산화공정은 전력용 GaN 전자소자의 누설전류감소와 항복전압 증가를 위한 후처리 공정으로 적합하다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.74-79
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• 2010

We have designed a millimeter-wave passive imaging sensor with multi-horn antenna array. Six horn array antenna is suggested that it is integrated into one housing, and this antenna is effectively configurated m space to assemble with LNA of WR-10 structure. Antenna is designed to have the peak gain of 17.5dBi at the center frequency of 94GHz, and the return loss of less than -25dB in W-band, and the small aperture size of $6mm{\times}9mm$ for antenna configuration with high resolution. LNA is designed to have total gain of more than 55dB and noise figure of less than 5dB for good sensitivity. We made a detector for DC output translation of millimeter-wave signal with zero bias Schottky diode. It is shown that good sensitivity of more than 500mV/mW.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.2
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• pp.5-11
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• 1974

Theoretical analysis is carried out for the beat frequency generation phenomena in the IMPATT diodes an4 the experimental studies are given in parrallel. The theory is based on the space charge modulation effect introduced to the multiplication process by the input signal. Computed results show that the beat frequency output power is linearly dependent upon the signal power and self oscillating power. Also the strong dependence of the output power with respect to the diode negative resistance is found and it turns out that the larger the negative resistance, the stronger the beat frequency output power. Experimental results show a good agreement with the theoretical values. Calculated conversion gain is about -0.4[db] at 10[GHz] and the experimental value shows -6.2[db] below this value. This difference between the theoretical and the experimental values is considered to be the results of the ineffective injection of signal power.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.412-415
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• 2015

This paper presents a MPPT(Maximum Power Point Tracking) control CMOS interface circuit for vibration energy harvesting. The proposed circuit consists of an AC-DC converter, MPPT Controller, DC-DC boost converter and PMU(Power Management Unit). The AC-DC converter rectifies the AC signals from vibration devices(PZT). MPPT controller is employed to harvest the maximum power from the PZT and increase efficiency of overall system. The DC-DC boost converter generates a boosted and regulated output at a predefined level and provides energy to load using PMU. A full-wave rectifier using active diodes is used as the AC-DC converter for high efficiency, and a schottky diode type DC-DC boost converter is used for a simple control circuitry. The proposed circuit has been designed in a 0.35um CMOS process. The chip area is $950um{\times}920um$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.345-353
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• 2011

An 1.485 Gbit/s video signal transmission system using the carrier frequency of H-band(220~325 GHz) was implemented and demonstrated for the first in domestic. The RF front-end was composed of Schottky barrier diode sub-harmonic mixers(SHM) and frequency triplers, and diagonal horn antennas for transmitter and receiver, respectively. The transmitted carrier frequency of 246 GHz was implemented in the H-band, and LO frequencies of H-band SHM is 120 GHz and 126 GHz for transmit and receive chains, respectively. The modulation scheme is ASK(Amplitude Shift Keying) where IF frequency is 5.94 GHz and the envelop detection was used in heterodyne receiver architecture, and direct detection receiver using ZBD(Zero Bias Detector) was implemented as well. The 1.485 Gbit/s video signal with HD-SDI format was successfully transmitted over wireless link distance of 5 m and displayed on HDTV at the transmitted average output power of 20 ${\mu}W$.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.180-180
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• 2000

Plasma source ion implantation is a new doping technique for the formation of shallow junction with the merits of high dose rate, low-cost and minimal wafer charging damage. In plasma source ion implantation process, the wafer is placed directly in the plasma of the appropriate dopant ions. Negative pulse bias is applied to the wafer, causing the dopant ions to be accelerated toward the wafer and implanted below the surface. In this work, inductively couples plasma was generated by anodized Al antenna that was located inside the vacuum chamber. The outside wall of Al chamber was surrounded by Nd-Fe-B permanent magnets to confine the plasma and to enhance the uniformity. Before implantation, the wafer was pre-sputtered using DC bias of 300B in Ar plasma in order to eliminate the native oxide. After cleaning, B2H6 (5%)/H2 plasma and negative pulse bias of -1kV to 5 kV were used to form shallow p+/n junction at the boron dose of 1$\times$1015 to 5$\times$1016 #/cm2. The as-implanted samples were annealed at 90$0^{\circ}C$, 95$0^{\circ}C$ and 100$0^{\circ}C$during various annealing time with rapid thermal process. After annealing, the sheet resistance and the junction depth were measured with four point probe and secondary ion mass spectroscopy, respectively. The doping uniformity was also investigated. In addition, the electrical characteristics were measured for Schottky diode with a current-voltage meter.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.267-270
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• 2014

This paper presents a CMOS interface circuit for vibration energy harvesting. The proposed circuit consists of an AC-DC converter and a DC-DC boost converter. The AC-DC converter rectifies the AC signals from vibration devices(PZT), and the DC-DC boost converter generates a boosted and regulated output at a predefined level. A full-wave rectifier using active diodes is used as the AC-DC converter for high efficiency, and a schottky diode type DC-DC boost converter is used for a simple control circuitry. A MPPT(Maximum Power Point Tracking) control is also employed to harvest the maximum power from the PZT. The proposed circuit has been designed in a 0.35um CMOS process. The chip area is $530um{\times}325um$. Simulation results shows that the maximum efficiencies of the AC-DC converter and DC-DC boost converter are 97.7% and 89.2%, respectively. The maximum efficiency of the entire system is 87.2%.

• Journal of IKEEE
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• v.26 no.1
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• pp.50-55
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• 2022

SiC is a power semiconductor with a wide bandgap, high insulation failure strength, and thermal conductivity, but many deep-level defects. Defects that appear in SiC can be divided into two categories, defects that appear in physical properties and interface traps that appear at interfaces. In this paper, Z_1/2 trap concentration 0 ~ 9×10¹⁴ cm^-3 reported at room temperature (300 K) is applied to SiC substrates and epi layer to investigate turn-on characteristics. As the trap concentration increased, the current density, Shockley-read-Hall (SRH), and Auger recombination decreased, and Ron increased by about 550% from 0.004 to 0.022 mohm.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.138-143
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• 2016

The designed and fabricated millimeter-wave security screening system receives radiation energy from an object and a human body. The imaging system consist of sixteen array antennas, sixteen four-stage LNAs, sixteen detectors, an infrared camera, a CCD camera, reflector, and a focusing lens. This system requires high sensitivity and wide bandwidth to detect the input thermal noise. The LNA module of the system has been measured to have 65.8 dB in average linear gain and 82 GHz~102 GHz in bandwidth to enhance the sensitivity for thermal noise, and to receive it over a wide bandwidth. The detector is used for direct current (DC) output translation of millimeter-wave signals with a zero bias Schottky diode. The lens and front-end of the millimeter-wave sensor are important in the system to detect the input thermal noise signal. The frequency range in the receiving sensitivity of the detectors was 350 to 400 mV/mW at 0 dBm (1 mW) input power. The developed W-band imaging system is effective for detecting and identifying concealed objects such as metal or plastic.