• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.111-114
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• 2005

The isolation performance of the S-band single-pole single-throw (SPST) monolithic microwave integrated circuit (MMIC) switch with two different RF-interconnection approaches, microstrip and grounded coplanar waveguide (GCPW) lines, are investigated. On-to-off isolation is improved by 5.8 dB with the GCPW design compared with the microstrip design and additional improvement of 6.9dB is obtained with the coplanar wire-bond interconnection (CWBI) at 3.4 GHz. The measured insertion loss and third-order inter-modulation distortion (IMD3) are less than 2.43 dB over 2.5 CHz $\sim$ 4 GHz and greater than 64 dBc.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.435-438
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• 2002

A design of Ku-band(11.7~12.20Hz) monolithic microwave integrated circuit(MMIC) low noise block(LNB) downconverter using self oscillating mixer (SOM) for direct broadcast satellite(DBS) application is presented The proposed LNB downconverter is composed of low noise amplifier(LNA), image reject filter(IRF), SOM , low pass filter(LPF). The conversion gain is 30dB , VSn is less than 1.7: 1 and overall noise figure is less than 1.2dB.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.654-657
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• 2002

This paper introduces the design and implementation of 40-㎓-band low noise amplifier (LNA) with ultra low gain flatness for wide-band wireless multimedia and satellite communication systems. The 40-㎓-band 4-stage LNA MMIC (Monolithic Microwave Integrated Circuit) demonstrates a small signal gain of more than 20 ㏈, an input return loss of 10.3 ㏈, and an output return loss of 16.3 ㏈ for 37$\square$42 ㎓. The gain flatness of the 40-㎓-band 4-stage LNA MMIC was 0.1 ㏈ for 37$\square$42 ㎓. The noise figure of the 40 ㎓-band LNA was simulated to be less than 2.7 dB for 37~42 ㎓. The chip size of the 4-stage LNA MMIC was 3.7${\times}$1.7 $\textrm{mm}^2$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.3
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• pp.264-272
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• 2009

In this paper, a Ka-band 10 W power amplifier module is designed and fabricated using MIC(Microwave Integrated Circuit) module technology which combines multiple power MMIC(Monolithic Microwave Integrated Circuit) chips on a thin film substrate. Modified Wilkinson power dividers/combiners are used for millimeter wave modules and CBFGC-PW-Microstrip transitions are utilized for reducing connection loss and suppressing resonance in the high-gain and high-power modules. The power amplifier module consists of seven MMIC chips and operates in a pulsed mode. for the pulsed mode operation, a gate pulse control circuit supplying the control voltage pulses to MMIC chips is designed and applied. The fabricated power amplifier module shows a power gain of about 58 dB and a saturated output power of 39.6 dBm at a center frequency of the interested frequency band.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.49-59
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• 2014

Effects of the dielectric constant and thickness of a feed substrate on the bandwidth and radiation characteristics of an aperture coupled microstrip patch antenna (ACMPA) are investigated. The optimized return loss bandwidth of an ACMPA increases without the degradation of radiation characteristics as the feed substrate dielectric constant increases for the same feed substrate thickness. The optimized return loss bandwidth of an ACMPA with the dielectric constant of a feed substrate of 10, which is compatible with the high dielectric constant monolithic microwave integrated circuit (MMIC) materials, increases without the degradation of radiation characteristics as the thickness of a feed substrate decreases. The ACMPA configuration is suitable for integration with MMICs.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.67-73
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• 2008

Reconfigurable radio technology is needed to reconstruct frequency and modem functionality, which can be different within various regions. In addition, it makes it possible for a single mobile handset to support various standards of wireless communication, and thus plays a key role inmobile convergence. A MMIC VCO(Monolithic Microwave Integrated Circuit Voltage Controlled Oscillator) has been developed to produce high power and wide bandwidth that adapts the Clapp-Gouriet type oscillator for series feedback. We were fabricated based on the 0.15um pHEMT from TRW. The MMIC VCO was connected to an alumina substrate on the carrier for testing. This MMIC VCO module shows good performance when compared with existing VCOs. Futhermore, it has potential as a reconfigurable MMIC VCO for ubiquitous communications such as LMDS (Local Multipoint Distribution Service), VSAT, Point to Point Radio and SATCOM.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.70-75
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• 2017

In this paper, we studied the RF characteristics of a voltage-controlled artificial transmission line employing periodically arrayed diodes for application to highly miniaturized wireless communication systems on an MMIC (monolithic microwave integrated circuit). According to the results, the novel voltage-controlled artificial transmission line employing periodically arrayed diodes exhibited a short wave length, which was only 35.2% that of the conventional transmission line, owing to increasing capacitance. In addition, it's effective permittivity and effective propagation constant exhibited considerably higher values than those of the conventional transmission line. Furthermore, attenuation constant of the voltage-controlled artificial transmission line was far higher than that of the conventional transmission line. Using the closed-form equation, we theoretically analyzed the equivalent circuit of the voltage-controlled artificial transmission line.

• Journal of electromagnetic engineering and science
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• v.17 no.2
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• pp.105-107
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• 2017

The self-biasing circuit through a feedback resistor is applied to a gallium nitride (GaN) distributed power amplifier (PA) monolithic microwave circuit (MMIC). The self-biasing circuit is a useful scheme for biasing depletion-mode compound semiconductor devices with a negative gate bias voltage, and is widely used for common source amplifiers. However, the self-biasing circuit is rarely used for PAs, because the large DC power dissipation of the feedback resistor results in the degradation of output power and power efficiency. In this study, the feasibility of applying a self-biasing circuit through a feedback resistor to a GaN PA MMIC is examined by using the high operation voltage of GaN high-electron mobility transistors. The measured results of the proposed GaN PA are the average output power of 41.1 dBm and the average power added efficiency of 12.2% over the 6-16 GHz band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.844-847
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• 2012

By using LHTL(Left-Handed Transmission Line) which is a form of a metamaterial and conventional RHTL (Right-Handed Transmission Line), we designed, fabricated and tested a broadband $90^{\circ}$ coupler which is a basic circuit for I-Q vector signal generation. Synthetic LHTL and RHTL were implemented with capacitors and inductors only, that the size is minimized. Also, by implementing a Wilkinson power divider which is required for the suggested circuit using a synthetic RHTL, the size of whole circuit is only $11mm{\times}12mm$. For the frequency range 0.8~1.25 GHz, the phase difference at the outputs maintained $90^{\circ}{\pm}5^{\circ}$ and thus, a broadband $90^{\circ}$ coupler could be made in a compact form. for the same frequency range, the insertion loss is less than 1.6 dB and return loss is more than 10.1 dB. To the best of our knowledge, this is the smallest and broadband $90^{\circ}$ coupler for the frequency range and if the circuit is made with MMIC(Monolithic Microwave Integrated Circuit) technology, the size will be reduced much further.

• Journal of electromagnetic engineering and science
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• v.16 no.1
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• pp.44-51
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• 2016

A commercial $0.25{\mu}m$ GaN process is used to implement 6-18 GHz wideband power amplifier (PA) monolithic microwave integrated circuits (MMICs). GaN HEMTs are advantageous for enhancing RF power due to high breakdown voltages. However, the large-signal models provided by the foundry service cannot guarantee model accuracy up to frequencies close to their maximum oscillation frequency ($F_{max}$). Generally, the optimum output load point of a PA varies severely according to frequency, which creates difficulties in generating watt-level output power through the octave bandwidth. This study overcomes these issues by the development of in-house large-signal models that include a thermal model and by applying distributed L-C output load matching to reactive matched amplifiers. The proposed GaN PAs have successfully accomplished output power over 5 W through the octave bandwidth.