• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.7
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• pp.7-13
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• 2001

The wirebonding is a common interconnection technique for modern microwave devices because of rather simple and reliable processes involved. At millimeter-wave frequencies, however, the bondwire parasitics are significant and consequently limit the external performance of packaged devices. In this paper, we represent wideband characterization of multiple bondwires and ribbon in a frequency range from 20 to 35 GHz. From these results, the double bondwire shows very small insertion loss less than 0.55 dB up to 35 GHz and its performance is comparable to that of the ribbon in the millimeter-wave frequencies. Therefore, the wirebonding is very suitable for millimeter wave packaging in terms of performance and manufacturing cost.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.7
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• pp.713-721
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• 2004

This paper presents a high Performance LNA based on InGaP/GaAs HBT for 5.4㎓ WAM band applications. During the past days, InGaP/GaAs HBT has been being used for mainly high power amplifiers, but InCaP/GaAs is recognized as a suitable device for RF single chip. At this point, the research about a high performance LNA based on InGaP/GaAs HBT must be preceded, and in this paper, a excellent linearity and noise characteristics LNA based on InGaP/GaAs HBT is desisted and fabricated. The LNA is integrated in new of 0.9${\times}$0.9$\textrm{mm}^2$ single chip with high Q spiral inductors and MIM capacitors. The proposed LNA is biased at current point for optimum noise figure and gain characteristics, futhermore, excellent linearity is achieved. The proposed LNA shows 13㏈ gain, 2.1㏈ noise figure, and excellent linearity in terms of IIP3 of 5.5㏈m.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.8
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• pp.752-758
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• 2004

This paper reports on the DC and RF characteristics of AlGaN/InGaN/GaN high electron-mobility transistors (HEMTs) grown by molecular beau epitaxy(MBE) on sapphire substrates. The devices with a 0.5 ${\mu}$m gate-length exhibited relatively flat transconductance(g$\_$m/), which results from the enhanced carrier confinement of the InGaN channel. The maximum drain current was 880 mA/mm with a peak g$\_$m/ of 156 mS/mm, an f$\_$T/ of 17.3 GHz, and an f$\_$MAX/ or 28.7 GHz. In addition to promising DC and RF results, pulsed I-V and current-switching measurements showed little dispersion in the unpassivated AlGaN/InGaN HEMTs. These results suggest that the addition of In to the GaN channel improves the electron transport characteristics as well as suppressing current collapse that is related to the surface trap states.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.135-140
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• 2009

This paper discusses how to change the electromagnetic waves' property in the cut-off causing discontinuity existing in the guiding structure of the RF passive component by using the metamaterial and elaborates on its principle. Particularly, we find and explain, from the viewpoint of electromagnetics and circuit theories, the so-called tunneling condition that when the segment with an extremely narrow cross-section leading to blockage in the parallel-plate waveguide is given the ENZ(Epsilon Near Zero) for its filling material, the wave starts to propagate through the segment. The analysis method as a transmission-line theory taking the discontinuity and material change into consideration is shown valid through the comparison with other methods for analyzing parallel-plate waveguides, and provides the illustration of the S-parameters and impedance describing the characteristics of the tunneling.

• Journal of Engineering Education Research
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• v.3 no.1
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• pp.12-20
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• 2000

In this paper, we are trying to explain an education method using the studio class where a lecturer can teach the theoretical approach for goals of theme, simulation for the theoretical results by using commercial CAD tools, and experiments for the simulation and design results. In order to apply the education skill using studio class to electrical engineering field efficiently, the theoretical approach, simulation procedure, and experiments should be coincided with each other. In this paper, the design procedure of low pass filter for undergraduate and graduate is chosen as an example of studio class In order to show the validity of the proposed education method. By considering the example, the efficiency of the method will be discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2443-2448
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• 2013

In this paper, a design of size-reduced microwave oscillator using common defected ground structure (common DGS) is described. At first, an oscillator is designed using the normal stub resonator, and the conventional DGS patterns are inserted for the first trial of size-reduction. Finally, the DGS resonator section is folded by half size in order to adopt the common DGS, and this produces the proposed size-reduced oscillator. Common DGS pattern is inserted for a better size-reduction than when conventional DGSs are used. The folded transmission line is connected using the 3-dimensional signal via-holes. For an example of design, a 2.1GHz oscillator is designed and fabricated using a small signal transistor and common DGS, which shows the size-reduction of 11 mm. The measurement shows 6.7dBm of output power and -133dBc/Hz@1MHz of phase noise. The measured performances are so similar to those of the oscillators before size-reduction and prove the proposed size-reduction method of oscillators using common DGS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.720-725
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• 2015

This paper describes the design of a wideband cascode amplifier using a feedback network and microwave small-signal transistors. The adopted cascode structure enables the miller effect to be lessened, cutoff frequency to increase, and reduction of gain in the mid-band to be mitigated. In addition, a feedback network is added to the cascode structure to improve the input matching and ripple performances over the wide operating band. The designed cascode amplifier contains a feedback network for small size and broadband amplification, whereas balanced amplifiers and distributed amplifiers have been used widely. The measurement shows $8.5dB{\pm}1.5dB$ of gain over 1000-2000MHz. The fabricated cascode amplifier has more than 8dB of gain over a 1000MHz bandwidth with a good flatness. The measured performances agree with the predicted ones even a minor shift in operating frequency is observed.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.1
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• pp.99-104
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• 2013

In this paper, we developed a fully integrated downconverter MMIC (monolithic microwave integrated circuit) including Lange coupler and output active balun for millimeter wave applications. Concretely, ${\lambda}$/4 transmission line was added to Lange coupler for size reduction of RF/LO input, and mixed RF/LO signals were applied to gate of the FET of mixer. Active balun was used at output port for a coupling of out-of-phase IF output signals. According to measured results, the proposed downconverter MMIC showed good RF performances. For example, the downconverter MMIC showed an LO leakage power of -25 dBc at IF output port, and a RF-LO isolation of 18 dB. Therefore, off-chip components such as LO rejection filters were not required for a normal operation of the proposed downconverter MMIC. The proposed downconverter MMIC showed a conversion gain of 10.3 dB at RF frequency of 63 GHz. The size of the downconverter MMIC including all active and passive components was $2.2{\times}1.4mm^2$.

• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.439-445
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• 2007

SiGe integrated circuits are being used in the field of high-speed wire/wireless communications and microwave systems due to the RF/high-speed analog characteristics and the easiness in the fabrication. Reducing the resistance variation in SiGe thin film resistors results in enhancing the reliability of integrated circuits. In this paper, we investigate the causes that generate the resistance nonuniformity after the silicon-based thin film resistor was fabricated, and consider the counter plan against that. Because the Ti-B precipitate, which formed during the silicide process of the SiGe thin film resistor, gives rise to the nonuniformity of SiGe resistors, the boron ions should be implanted as many as possible. In addition, the resistance deviation increases as the size of the contact hole that interconnects the SiGe resistor and the metal line decreases. Therefore, the size of the contact hole must be enlarged in order to reduce the resistance deviation.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.45-51
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• 2008

This paper presents theoretical and experimental analysis on the characteristics of the power spectrum of electormagnetic waves radiating from the spark plug and their cables of a distributorless ignition system. The theoretical study was conducted applying the microwave transmission line theory and the antenna theory. The experimental works were carried out to measure the standing wave ratio(SWR) and the radiation power spectrum of this system. As a result, it has been found that a spark plug and its cable is working as a monopole antenna radiating elelctromagnetic waves. Because of its similar structure to a monopole antenna, the envelope of radiation power spectrum distribution has a bell shape which can be obtained from a monopole antenna operating as a series resonant circuit. The frequency characteristics from the SWR measurements show a similar frequency characteristics of power spectrum of the system studied. Also, it has been found that the density of the power spectrum of the system fitting a long time used spark plug is higher than that of fitting a new spark plug.