• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06a
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• pp.27-31
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• 1996

In this paper, The SSPA(Solid State Power Amplifier) is 100 watts amplifier which is used with C-Band Satellite communication Up-Link frequency, 5.875 ∼6.425 GHz. SSPA requires more output power than is available from a single GaAs FET with result it is necessary to combine the output of many device. To achieve a high power, it is important to make a good N-way power divider which has a small different phase, good combining efficiency and high power handling capability. The reliability of Power GaAs FET decrease with increasing junction temperature, power amplifier in general dissipate amount of power. It is important to provide them with a heatsink and a temperature compensation circuit to dispose of the unwanted heat. To compensate temperature, Using PIN diode attenuator, it is enable to get a precision gain control. The output power of the SSPA is more than 100 watt with which the TWTA (Traveling-Wave Tube Amplifier) can be replaced. Each stage was measured by the Network analyzer PH8510C, Power meter Booton 42BD, The gain is more than 53 dB, flatness is less than 1.5 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.540-545
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• 2015

This paper presents the design, fabrication and measurement results of a S-band internally-matched power amplifier using Gallium Nitride High Electron Mobility Transistor(GaN HEMT) die. In order to fabricate the S-band internally-matched power amplifier, a high dielectric substrate and alumina were used for input/output matching circuits. The measured output power is 55.4 dBm, the drain efficiency is 78 % and the power gain is 11 dB under pulse operation at the frequency of 3 GHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.993-998
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• 2002

At Power amplifier, distortion of output is appeared because of non-linearlity, so we must study method of compensation for non-linearity. In this paper, it was studied about the characteristic of predistorter using serial schottky diode for an amplifier. As a result, we confirmed that power amplifier was able to linearize when we put predistorter using non-linearity of schottky diode before power amplifier. When input carrier level was low, input carrier was delivered directly into power amplifier but input carrier level was high, input carrier was delivered into power amplifier through predistorter with suppressed level. As a result power amplifier always was at saturation region. Through simulation using serenade 8.0, we have concluded that efficiency was improved about 3%, and predistorter got best linearity at 1.8㎓ between 800㎒∼2.2㎓.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.2
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• pp.235-245
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• 2014

This paper presents an envelope tracking power amplifier using a standard CMOS process for the 3GPP long-term evolution transmitters. An efficiency of the CMOS power amplifier for the modulated signals can be improved using a highly efficient and wideband CMOS bias modulator. The CMOS PA is based on a two-stage differential common-source structure for high gain and large voltage swing. The bias modulator is based on a hybrid buck converter which consists of a linear stage and a switching stage. The dynamic load condition according to the envelope signal level is taken into account for the bias modulator design. By applying the bias modulator to the power amplifier, an overall efficiency of 41.7 % was achieved at an output power of 24 dBm using the 16-QAM uplink LTE signal. It is 5.3 % points higher than that of the power amplifier alone at the same output power and linearity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5409-5415
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• 2012

Piezo ceramic actuator is used for various industrial products such as spray, dispenser, and valve control etc. Since the deflection of the piezo ceramic element depends on the applied voltage, it is required a power amplifier with high voltage supply for driving the piezo ceramic actuators. In this paper, we develop a simple H-bridge type power amplifier and a compact flyback type high voltage switching mode power supply for piezo ceramic actuators. It is easy to adjust the amount of energy input to piezo ceramic actuator by pulse-width-modulation with H-bridge type power amplifier.

• Journal of electromagnetic engineering and science
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• v.11 no.1
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• pp.16-26
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• 2011

This paper presents high power and high efficiency Doherty amplifiers for 2.345 GHz wireless broadband (WiBro) applications that use a Nitronex 125-W ($P_{3dB}$) GaN high electron mobility transistor (HEMT). Two- and three-way Doherty amplifiers and a saturated Doherty amplifier using Class-F circuitry are implemented. The measured result for a center frequency of 2.345 GHz shows that the two-way Doherty amplifier attains a high $P_{3dB}$ of 51.5 dBm, a gain of 12.5 dB, and a power-added efficiency (PAE) improvement of about 16 % compared to a single class AB amplifier at 6-dB back-off power region from $P_{3dB}$. For a WiBro OFDMA signal, the Doherty amplifier provides an adjacent channel leakage ratio (ACLR) at 4.77 MHz offset that is -33 dBc at an output power of 42 dBm, which is a 9.5 dB back-off power region from $P_{3dB}$. By employing a digital pre-distortion (DPD) technique, the ACLR of the Doherty amplifier is improved from -33 dBc to -48 dBc. The measured result for the same frequency shows that the three-way Doherty amplifier, which has a $P_{3dB}$ of 53.16 dBm and a gain of 10.3 dB, and the saturated Doherty amplifier, which has a $P_{3dB}$ of 51.1 dBm and a gain of 10.3 dB, provide a PAE improvement of 11 % at the 9-dB back-off power region and 7.5 % at the 6-dB back-off region, respectively, compared to the two-way Doherty amplifier.

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.358-364
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• 2009

This paper shows some variable bias techniques which can improve the power added efficiency(PAE) for the designed power amplifier. Some simulations have been done to get the effect of the bias change, and variable bias is adopted to get the higher efficiency for dual mode amplifier which generates two different output power levels. With drain bias change and a fixed gate bias, the amplifier shows PAE improvement compared to the fixed bias amplifier. In addition, this paper analyzed nonlinear distortion of the power amplifier and has used the digital predistortion which can result in 10dB ACPR improvement for the dual band amplifier.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.11
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• pp.1262-1270
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• 2007

In this paper, we propose a new distortion cancellation mechanism for a balanced power amplifier structure using the carrier cancellation loop of a feedforward and post-distortion technique. The proposed cross post-distortion balanced linear amplifier can reduce nonlinear components as much as the conventional feedforward amplifier through the output dynamic range and broad bandwidth. Also the proposed system provides higher efficiency than the feedforward. The capacities of power amplifier and error power amplifier in the proposed system are analyzed and compared with those of feedforward amplifier. Also the operation mechanisms of the three kind loops are explained. The proposed cross post-distortion balanced linear power amplifier is implemented at the IMT-2000($f_0=2.14\;GHz$) band. With the commercial high power amplifiers of total power of 240 W peak envelope power fer base-station application, the adjacent channel leakage ratio measurement with wideband code division multiple access 4FA signal shows 18.6 dB improvement at an average output power of 40 dBm. The efficiency of fabricated amplifier Improves about 2 % than the conventional feedforward amplifier.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.826-831
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• 2009

In this paper, a high power RF amplifier module using AlN substrate of high thermal conductivity has been proposed. This RF amplifier module has the advantage of compact size and effective heat dissipation for the packaging of high power chip. To fabricate the thru-hole and scribing line on AlN substrate, the key parameters of $CO_2$ laser were experimented. And then, microstrip lines and spiral planar inductors were fabricated on an AlN substrate using the thin-film process. The fabricated microstrip lines on the AlN substrate has an attenuation value of 0.1 dB/mm up to 10 GHz. The fabricated spiral planar inductor has a high quality factor, a maximum of about 62 at 1 GHz for a 5.65 nH inductor. Packaging of a RF power amplifier was implemented on an AlN substrate with thru-hole. From the measured results, the gain is 24 dB from 13 to 15 GHz and the output power is 33.65 dBm(2.3 W).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.394-402
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• 2013

This paper presents design, fabrication and ruggedness test of switching-mode power amplifier using GaN(Gallium Nitride) HEMT(High Electron Mobility Transistor) for S-band radar applications. The power amplifier is designed to Class-F for high efficiency. The input signal for the measurement of the power amplifier is pulse signal at $100{\mu}s$ pulse width and duty cycle of 10 %. The measurement results of the fabricated Class-F power amplifier are a power gain of 10.8 dB, an output power of 40.8 dBm, a power added efficiency(PAE) of 54.2 %, and a drain efficiency of 62.6 %, at the center frequency. We proposed reliability test set-up of a power amplifier for ruggedness test. And we measured output power and efficiency according to VSWR(Voltage Standing Wave Ratio) variation. The designed power amplifier achieved output power of 32.6~41.1 dBm and drain efficiency of 23.4~63 % by changing VSWR, respectively.