• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2145-2147
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• 1998

This paper presents a Class-D type switched mode audio power amplifier employing ZVT(Zero-Voltage-Transition) soft switching technique. In order to obtain a wide bandwidth and lower distortion for an audio amplifier a high switching frequency is essential. The ZVT switching scheme enables a high frequency switching without sacrificing the efficiency much as in a hard switching. A prototype amplifier is built to demonstrate the feasibility of this technique for the audio power amplifier.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11A
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• pp.902-911
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• 2003

Using InGaP/GaAs HBT power cells with a 2.0${\times}$20$\mu\textrm{m}$$^2$ emitter area of a unit HBT, a two stage MMIC power amplifier has been developed for IMT-2000 handsets. An active-bias circuit has been used for temperature compensation and reduction in the idling current. Fitting on measured S-parameters of the HBT cells, circuit elements of HBT's nonlinear equivalent model have been extracted. The matching circuits have been designed basically with the extracted model. A two stage HBT MMIC power amplifier fabricated using ETRI's HBT process. The power amplifier produces an 1-㏈ compressed output power(P$\_$l-㏈/) of 28.4 ㏈m with 31% power added efficiency(PAE) and 23-㏈ power gain at 1.95 GHz in on-wafer measurement. Also, the power amplifier produces a 26 ㏈m output power, 28% PAE and a 22.3-㏈ power gain with a -40 ㏈c ACPR at a 3.84 ㎒ off-center frequency in COB measurement.quency in COB measurement.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.637-640
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• 1998

A 35 ㎓ GaAs MMIC power amplifier was designed using a monolithic technology with AlGaAs/InGaAs/GaAs power PM-HEMTs, rectangualr spiral inductors and Si3N4 MIM capacitors. The GaAs power MESFETs in the input and output stages have total gate widths of 120 um and 320 um, respectively. Total S21 gain of 10.82dB and S11 of -16.26 dB were obtained from the designed MMIC power amplifier at 35 ㎓. And the chip size of the MMIC amplifier was 1.4$\times$0.8 $\textrm{mm}^2$

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.4
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• pp.426-432
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• 2012

A fully-integrated low power K-band radar transceiver in 130 nm CMOS process is presented. It consists of a low-noise amplifier (LNA), a down-conversion mixer, a power amplifier (PA), and a frequency synthesizer with injection locked buffer for driving mixer and PA. The receiver front-end provides a conversion gain of 19 dB. The LNA achieves a power gain of 15 dB and noise figure of 5.4 dB, and the PA has an output power of 9 dBm. The phase noise of VCO is -90 dBc/Hz at 1-MHz offset. The total dc power dissipation of the transceiver is 142 mW and the size of the chip is only $1.2{\times}1.4mm^2$.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1306-1308
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• 2000

A new ZVT PFC for using 3[KW] power amplifier is proposed. Generally, the single phase diode rectifier has been widely used in the SMPS of the conventional power amplifier. But this rectifier has occurred some problems which are the input power factor and current harmonics. To solve the above problems, in this paper, two topology is adopted. The one is the boost type PFC for improving the input power factor. The other is the ZVT resonant circuit for reducing the switching loss and stress. In this paper, the proposed topology is analyze designed to built the ZVT PFC for using 3[KW] power amplifier. In order to verify the circuit va finally, the PSPICE simulation and experiment results are presented.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.575-582
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• 2007

In this paper, a 100 Watt high power amplifier has been implemented and performed evaluation, which is operating at UHF band ($470\;{\sim}\;806\;MHz$) for Digital TV repeater. To achieve increase of bandwidth and high power capability, 3-way power combiner and divider of Wilkinson type was adopted. In order to measure the fabricated 100 Watt power amplifier, the estimation technique function which makes equivalent mask was used. As a result of the measurement, the existence of pilot signal is confirmed and the signal transmitted at the rated output power 100 Watt is brought out the flat feature through 6 MHz bandwidth. and it resulted that its value was less than -47 dB at the edge of radiation channel and less than -110 dB at more than 6 MHz position from channel edge.

• Journal of IKEEE
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• v.23 no.2
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• pp.454-460
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• 2019

In this paper, a watt-level 2.4-GHz RFCMOS linear power amplifier (PA) with pre-distortion method using variable capacitance with respect to input power is demonstrated. The proposed structure is composed of a power detector and a MOS capacitor to improve the linearity of the PA. The pre-distortion based linearizer is embedded in the two-stage PA to compensate for the gain compression in the amplifier stages, it also improves the output P1dB by approximately 1 dB. The simulation results demonstrate a 1-dB gain compression power of 30.81 dBm at 2.4-GHz, and PAE is 29.24 % at the output P1dB point.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.2
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• pp.125-131
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• 2002

This paper presents MMIC drive and power amplifiers covering 6-18 ㎓. For simple wideband impedance matching and less sensitivity to fabrication variation, modified distributed topologies are employed in the both amplifiers. Cascade amplifiers with a self-biasing circuit through feedback resistors are used as unit gain blocks in the drive amplifier, resulting in high gain, high stability, and compact chip size. Self impedance matching and high-pass, low-pass impedance matching networks are used in the power amplifier. In measured results, the drive amplifier showed good return losses ($S_11,{\;}S_{22}{\;}<{\;}-10.5{\;}dB$), gain flatness ($S_{21}={\;}16{\;}{\pm}0.6{\;}dB$), and $P_{1dB}{\;}>{\;}22{\;}dBm$ over 6-18 GHz. The power amplifier showed $P_{1dB}{\;}>{\;}28.8{\;}dBm$ and $P_{sat}{\;}{\approx}{\;}30.0{\;}dBm$ with good small signal characteristics ($S_{11}<-10{\;}dB,{\;}S_{22}{\;}<{\;}-6{\;}dB,{\;}and{\;}S_{21}={\;}18.5{\;}{\pm}{\;}1.25{\;}dB$) over 6-18 GHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2241-2248
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• 2011

This paper describes the design of a palette-type 60watt high power amplifier module using gallium nitride(GaN) devices with high power and efficiency performances for WiMAX and LTE systems. The line-up for the high gain amplifier module consists of the pre-amplifier stage with low power and high gain, 8watt GaN driving amplifier stage, and 60watt GaN high power amplifier stage of Doherty structure with two 30watt GaN devices. The obtained gain is 61.4dB with an excellent gain flatness of ${\pm}$0.075dB over 2.5~2.68GHz. GaN devices and the Doherty structure are adopted for the improvement of high efficiency and output power. The measurement for the fabricated high power amplifier module of palette type is performed using the widely known WiMAX signal all over the world. In the example of RRH(remote radio head) application of the fabricated amplifier module, the measured efficiency is 37~38% with the 10watts of modulated output power. It is shown that when the fabricated amplifier module is activated with a digital predistorter(DPD), the measured ACLR is better than 46dBc under the 10watts of modulated output power.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.91-96
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• 2005

In this paper, describes the design and performance of a 1.5 kW solid-state pulsed power amplifier, operating over 2.7-2.9 GHz at a duty of 10% and with a pulse width of 100 us for radar application. The solid-state pulsed power amplifier configures a series of 8-stage cascaded power amplifier with different RF output power levels. Low loss Wilkinson combiners are used to combine output powers of six 300W high power solid state modules. Tests show peak output power of 1.61 kW, corresponding to PAE of 26.2% over 2.7-2.9 GHz with pulse width of 100 us and a PRF of 1 kHz.