• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.3
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• pp.40-47
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• 2009

This paper presents new drain bias scheme for the linearity enhancement of envelope tacking power amplifiers for W-CDMA base-stations. In the conventional envelope tracking power amplifiers, the drain bias voltage is lowered close to the knee voltage of transistor, resulting in the severe linearity degradation. To solve this problem, it is proposed in this paper that the amplifier is biased in the conventional class AB mode with a fixed drain bias voltage if the input envelope is low and in the envelope tracking mode otherwise. Moreover, the drain bias in the envelope tracking mode is newly determined to minimized the distortion. To verify the effectiveness of the proposed bias scheme, simulation is performed on the W-CDMA based-station envelope tracking power amplifier using class AB Si-LDMOS power amplifier. It is shown from the simulation that the proposed bias scheme allows a drastic linearity enhancement with the comparable efficiency enough to meet the requirement of W-CDMA base-station without additional linearization techniques.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.5
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• pp.72-79
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• 2010

In this paper, we describe the design and implementation of a high efficiency Doherty power amplifier using gallium nitride (GaN) high-electron mobility transistor (HEMT). The carrier and peaking amplifiers of the proposed Doherty power amplifier consist of the switching-mode Class-E power amplifiers. The test conditions are a duty of 10% and a pulse width of $100\;{\mu}s$ and pulse repetition frequency (PRF) of 1 kHz for a S-band radar application. A RF performance peak PAE of 64% with drain efficiency of 80.6%, at 6 dB output back-off point from saturated output power of 45.5 dBm, was obtained at 2.85 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.807-813
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• 2008

The gate-biases of the Doherty power amplifier are controlled to improve the linearity performance. The linearity improvement mechanism of the Doherty amplifier is the harmonic cancellation of the carrier and peaking amplifier at the output power combining point. However, it is difficult to cancel the harmonic power for the broader power range because the condition for cancelling is varied by power. For the linearity improvement, we have explored the linearity characteristic of the Doherty amplifier according to the input power and gate biases of the carrier and peaking amplifier. To extend the region of harmonic power cancellation, we have injected the proper gate bias to the carrier and peaking amplifier according to the input power levels. To validate the linearity improvement, the Doherty amplifier is designed using Eudyna 10-W PEP GaN HEMT EGN010MKs at 2.345 GHz and optimized to achieve a high linearity and efficiency at an average output power of 33 dBm, backed off about 10 dB from the $P_{1dB}$. In the experiments, the envelope tracking Doherty amplifier delivers a significantly improved adjacent channel leakage ratio performance of -37.4 dBc, which is an enhancement of about 2.8 dB, maintaining the high PAE of about 26 % for the WCDMA 1-FA signal at an average output power of 33 dBm. For the 802.16-2004 signal, the amplifier is also improved by about 2 dB, -35 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.7
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• pp.1156-1160
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• 2000

The cancellation loop configuration for power amplifier module is proposed to reject the RX signals using feed-forward technique. In this paper, we implement the 1W-ampilfier module of WLL band to show validity of the proposed cancellation loop. The power amplifier module with the proposed cancellation loop can provide low TX insertion path loss due to duplexer and choice of loose RX attenuation characteristic for various wireless communication systems. It shows at least 90 % improved RX rejection characteristic compared to power amplifier module without RX band cancellation loop.

• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.167-172
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• 2006

In this paper, the 25W power amplifier for UHF band radio transceiver has been designed and realized. The power amplifier was composed of drive, power amplifier and control stages. Feedback topology and coaxial line baluns were used for wide band operation. The VDMOS, which has reliable performance for linearity and efficiency, was used for power device and designed to operate as push-pull amplification at Class AB Bias. The power amplifier designed in such a way was found to show stable AM modulation performance when voice signal was detected at the gate stage, with being designed and realized to meet output specifications of commercial air traffic control transmitter.

• Journal of Advanced Navigation Technology
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• v.18 no.3
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• pp.229-235
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• 2014

This paper presents the Doherty power amplifier with a digitally controlled analog predistorter circuit of Scintera Corp. to produce high power efficiency and high linearity performance. The analog predistorter improves the linearity performance because of controlling amplitude and phase values of input signal in order to improve intermodulation performance of power amplifier. Also, the power amplifier is designed by the Doherty technology to obtain the high efficiency performance. To validate the Scintera's analog predistorter, we are implemented the power amplifier with Doherty method at center frequency 2150 MHz. Compared with the balanced amplifier, the power amplifier is improved above 11% enhanced efficiency and more than 15 dB ACPR improvement.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.693-695
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• 2015

The design and implementation of a broadband and linear HPA for TVWS are presented in this paper. The spectrum mask and transmitted power of HPAs for TVWS must be controlled and meet the regulations to minimize interference effects on the present broadcasting systems. The implemented HPA has the operating frequency of 470 ~ 698MHz with the maximum 48.63dB and minimum 43.45dB gain, input reflection coefficient of below -21.32dB, output reflection coefficient of below -4.29dB and the linearity of -45.24dBc at 28.79dBm output power.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.10
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• pp.613-615
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• 2014

The design and implementation of a broadband and linear HPA(High Power Amplifier) for TVWS are presented in this paper. The spectrum mask and transmitted power of HPA for TVWS must be controlled and meet the regulations to minimize interference effects on present broadcasting systems. The implemented HPA has the operating frequency of 460 ~ 698MHz with $24.7{\pm}1dB$ gain, input reflection coefficient of below -25dB, output reflection coefficient of below -7.28dB and the linearity of -57.7dBc at 22.2dBm output power.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10B
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• pp.1701-1706
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• 2000

In this work a 38 GHz hybrid 2-stage power amplifier module using GaAs pHEMTs and waveguide to microstrip transitions has been successfully developed. A 10 mil thickness duroid substrate was use for fabrication of the power amplifier and the waveguide to microstrip transitions. The fabricated waveguide to microstrip transition showed about 1 dB insertion loss(back to back) at 32-40 GHz. The measured results of power amplifier module showed 29 dBm output power(P1.5dB), 7,2 dB associated gain and 11.2% power-added efficiency(PAE) at 36.8-38.5 GHz.

• Journal of IKEEE
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• v.24 no.4
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• pp.1093-1097
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• 2020

This work describes the design and characterization of a Ku-band monolithic microwave integrated circuit (MMIC) power amplifier (PA) for satellite communication applications. The device technology used relies on 0.25 ㎛ gate length gallium arsenide (GaAs) pseudomorphic high electron mobility transistor (PHEMT) of wireless information networking (WIN) semiconductor foundry. The developed Ku-band PHEMT MMIC power amplifier has a small-signal gain of 22.2~23.1 dB and saturated output power of 34.8~35.4 dBm over the entire band of 13.75 to 14.5 GHz. Maximum saturated output power is a 35.4 dBm (3.47 W) at 13.75 GHz. Its power added efficiency (PAE) is 30.6~37.83% and the chip dimensions are 4.4 mm×1.9 mm. The developed 3 W PHEMT MMIC power amplifier is expected to be applied in a variety of Ku-band satellite communication applications.