• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.8
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• pp.409-413
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• 2001

In the electron-gun of CRT, the Mo-tip FEA was employed as cold cathode in order to replace the conventional thermal cathode. The Mo-tip FEA was designed and fabricated according to CRT specification and mounted on the electron-gun. It was known that fabricated cold cathode electron-gun showed better performance in terms of maximum emission current and switch-on time when compared with the ones of thermal cathode electron-gun, but some geometrical structures in the inside of electron-gun must be changed to reduce the gate leakage current. Finally, the potential applicability was guaranteed by means of operating the 19 inch-sized LG-color CRT using the fabricated cold cathode electron-gun.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.3
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• pp.193-197
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• 2013

This paper presents a 5-bit true time delay circuit using a standard 0.18 ${\mu}m$ CMOS process for the broadband phased array antenna without the beam squint. The maximum time delay of ~106 ps with the delay step of ~3.3 ps is achieved at 5-20 GHz. The RMS group delay and amplitude errors are < 1 ps and <2 dB, respectively. The measured insertion loss is <27 dB and the input and output return losses are <12 dB at 5-15 GHz. The current consumption is nearly zero with 1.8 V supply. The chip size is $1.04{\times}0.85\;mm^2$ including pads.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.1
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• pp.46-49
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• 1986

A 32x32 liquid crystal (LC) flat panel display using two-dimensional array of PMOS switches and capacitors is designed and fabricated. Standard PMOS process was followed to fabricate the switch and capacitor array on silicon wafer, on the top of which guest-host effect liquid crystal was wmployed as an electro-optical material for optical switching and liquid crystal display(LCD) with its external drive circuitry was basically successful. Remaining problems to be solved are improvement of contrast ratio, good surface alignment and uniformity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.439-446
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• 2004

This paper describes high speed and low power design techniques for an 8-bit 500MSamples/s CMOS 2-step ADC. Instead of the conventional closed-loop architecture, the newly proposed ADC adopts open-loop architecture and uses a reset-switch to reduce loading time in an environment of big parasitic-capacitances of mux-array. An analog-latch is also used to reduce power consumption. Simulation result shows that the ADC has the SNDR of 46.91㏈ with a input frequency of 103MHz at 500Msample/s and consumes 203㎽ with a 1.8V single power supply. The chip is designed with a 0.18mm 1-poly 6-metal CMOS technology and occupies active area of 760${\mu}{\textrm}{m}$*800${\mu}{\textrm}{m}$.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.5
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• pp.81-92
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• 2013

The satellite includes many release mechanisms such as solar array deployment, antenna deployment, cover to protect contamination in scientific equipment, pyro value of the propulsion subsytem, and bypass device in Li-Ion cell module. A drive the initiators is a critical to the successful mission because the initiators of release mechanism driving by the pyrotechnic circuit is operated in single short. The pyrotechnic circuit has to provide switching network for safety. A typical switching network has defect consisting of high current rating fire switch to handle switching transient current during fire the initiator. The pyrotechnic circuit is required some form of power conditioning to reduce the peak power demanded from the bus if the initiators are to be fired from the main bus. This paper design a pyrotechnic circuit synchronized to the fire-command to activate the fire switch to overcome use high current rating fire switch to handle switching transient current during fire the initiator. The pyrotechnic circuit provides a current limited widow pulse for fire current synchronized to the fire-command to insure that fire switch will only carry the current but never switch it. The current limited widow pulse for fire current can be possible to use low current rating and light mass switch in switching network. The current limit function in the pyrotechnic circuit reduces supply voltage to initiator and provides the effect of power conditioning function to reduce peak bus power. The pyrotechnic circuit to apply satellite development on geostationary orbit is verified the function by test in development model.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.86-90
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• 2014

A DC-DC Converter operates in CCM(Continuous Coundcution Mode), DCM(Discontinuous Conduction Mode), CRM(Critical Conduction Mode). The CRM is boundary between CCM and DCM. If a DC-DC converter is designed to operate in CRM, its inductor volume can decrease and power loss which caused by switch and diode can decrease. In this paper, the DC-DC converter which operates in CRM is applied to a solar array regulator(SAR) for the satellite. The switching frequency of the CRM boost SAR changes according to input and output condition. The switching frequency limit logic is applied to limit the maximum switching frequency. Meanwhile, the small signal transfer function of the CRM boost SAR is simple, so the controller design is also simple. In this paper, the small signal transfer function from control reference to solar array voltage is induced. And the voltage controller is designed based on the small signal transfer function. Finally, the CRM boost SAR is verified by simulation.

• Korean Journal of Optics and Photonics
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• v.13 no.4
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• pp.289-294
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• 2002

We propose optical true time-delays (TTDs) for phased-array antennas (PAAs) composed of 2${\times}$2 MEMS switches and fiber delay lines, and implement a TTD which shows a maximum scan angle of $120^{o}$ with $30^{o}$ resolution. Since this structure uses only one fixed wavelength laser diode, it provides several advantages such as easy control, high speed operation, and low cost compared with those of the optical TTDs using tunable laser sources. We design a four element linear PAA using the proposed TTDs at 10 ㎓. Simulation results show that the maximum gain is 11.6 dB at the radiation angle $0^{o}$, 11.2 dB at $\pm$$30^{o}$, and 10.6 dB at $\pm$$60^{o}$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.5
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• pp.9-14
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• 2009

In this paper, we proposed a novel OTP unit bit of CMOS gate oxide antifuse using the standard CMOS process without additional process. The proposed OTP unit bit is composed of 3 transistors including an NMOS gate oxide antifuse and a sense amplifier of inverter type. The layout area of the proposed OTP unit bit is $22{\mu}m^2$ similar to a conventional OTP unit bit. The programming time of the proposed OTP unit bit is 3.6msec that is improved than that of the conventional OTP unit bit because it doesn't use high voltage blocking elements such as high voltage blocking switch transistor and resistor. And the OTP array with the proposed OTP unit bit doesn't need sense amplifier and bias generation circuit that are used in a conventional OTP array because sense amplifier of inverter type is included to the proposed OTP unit bit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.347-350
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• 2017

In this paper, we implemented a real-time 2.4 GHz direction finding system using a time-modulated array(TMA) and an Universal Software Radio Peripheral(USRP). Our system consists of two commercial monopole antennas, self-designed switch board, and an USRP, and it is controlled using LabVIEW program in real-time. From measured results, it is verified that our system can exactly detect the incident angle within 4 degree in the range of 30 degree. Our direction finding system has advantages of a simple hardware architecture than conventional one with multiple receivers, and a simple algorithm only by using a main lobe and a first side-lobe of switching frequency.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.49-55
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• 2013

A high-voltage highly-integrated analog front-end (AFE) IC for medical ultrasound imaging applications is implemented using standard 0.18-${\mu}m$ CMOS process. The proposed AFE IC is composed of a high-voltage (HV) pulser utilizing stacked transistors generating up to 15 Vp-p pulses at 2.6 MHz, a low-voltage low-noise transimpedance preamplifier, and a HV switch for isolation between the transmit and receive parts. The designed IC consumes less than $0.15mm^2$ of core area, making it feasible to be applied for multi-array medical ultrasound imaging systems, including portable handheld applications.