• Journal of IKEEE
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• v.22 no.4
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• pp.1050-1055
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• 2018

In this paper, we analyzed the sensitivity of matching elements for the dual-band operation of a power amplifier with composite right/left-handed (CRLH) transmission lines. Metamaterial theory enables CRLH transmission to support arbitrary impedance matching at dual frequencies. In general, at sub-GHz range, the CRLH matching networks are commonly implemented with lumped elements, which are prone to manufacturing distribution. In order to reduce the effect from the distribution of element values in design, we suggest a method to analyze the sensitivity of matching elements from the performance aspect of power amplifiers. Based on the analysis, a 40dBm dual-band power amplifier operating at 0.7GHz and 1.5GHz is designed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1030-1039
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• 2006

A high power and high gain Doherty amplifier is designed by using embedded driver amplifiers in the final stage. The operational characteristics of a two-stage Doherty amplifier are analyzed, as a function of the two-stage peaking amplifier gate biases. The driver stages and final output stages are implemented using two single-ended MRF21045s and a single push-pull packaged MRF5P21180, respectively. This two-stage Doherty amplifier demonstrated 27 dB gain with a PAE of 23 % at 15 W average output power.

• Smart Structures and Systems
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• v.7 no.5
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• pp.365-378
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• 2011

Piezo-based active structural health monitoring (SHM) requires amplifiers specifically designed for capacitive loads. Moreover, with the increase in number of applications of wireless SHM systems, energy efficiency and cost reduction for this type of amplifiers is becoming a requirement. General lab grade amplifiers are big and costly, and not built for outdoor environments. Although some piezoceramic power amplifiers are available in the market, none of them are specifically targeting the wireless constraints and low power requirements. In this paper, a piezoceramic transducer amplifier for wireless active SHM systems has been designed. Power requirements are met by two digital On/Off switches that set the amplifier in a standby state when not in use. It provides a stable ${\pm}180$ Volts output with a bandwidth of 7k Hz using a single 12 V battery. Additionally, both voltage and current outputs are provided for feedback control, impedance check, or actuator damage verification. Vibration control tests of an aluminum beam were conducted in the University of Houston lab, while wireless active SHM tests of a wind turbine blade were performed in the Harbin Institute of Technology wind tunnel. The results showed that the developed amplifier provided equivalent results to commercial solutions in suppressing structural vibrations, and that it allows researchers to perform active wireless SHM on moving objects with no power wires from the grid.

• Journal of Advanced Navigation Technology
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• v.12 no.3
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• pp.220-226
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• 2008

This paper proposes the Reconfigurable Doherty Amplifier(RDA) with asymmetric structure which has ${\lambda}/4$ impedance transformer for modulating the load impedance in peaking amplifier path. This structure is possible to implement a compact size for N-stage multi Doherty amplifier and to get almost same characteristics that is compared to conventional Doherty amplifier. To realize the high efficiency amplifier, we were implemented 45 Watts power amplifier at transmitter band of Wideband Code Division Multiple Access(WCDMA) base-station. As a result, in case of WCDMA 1 Frequency Allocation(FA) input signals, this amplifier has obtained a 26.3% Power Added Efficiency(PAE) at 8 dB back-off point from P1dB and an Adjacent Channel Leakage Power(ACLR) is -40.4 dBc at center frequency ${\pm}5MHz$ deviation.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.110-114
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• 2017

Using a small mobile wireless network as a supplement to the disaster safety network can be useful for eliminating small radio shadowing areas, reducing traffic overloads in disaster areas, and quickly building a disaster communication network in difficult access areas. Potable base station is needed to build a small mobile wireless network, and the portable base station using TVWS(TV White Space) is effective in terms of utilization of radio frequency resources and construction cost of wireless networks. In this paper, we design and implement a power amplifier for portable base station operating in TVWS. The implemented power amplifier operates at 470 ~ 698MHz. The gain of the implemented amplifier is more than 20.1dB, the input/output return loss is more than 11.4dB, and the isolation is more than 39.9dB when the output is off. The IMD characteristic of the power amplifier has characteristics of 61.0dBc with 18.8dBm output at 470MHz, 59.3dBc wih 18.6dBm output at 550MHz and 56.5dBc with 19.0dBm output at 690MHz. The power amplifier implemented in this paper can be used as a power amplifier for portable base station.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.22-29
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• 2009

In this paper, we developed the 200-Watts SSPA(Solid State Power Amplifier) for the X-band pulse compression solid state radar. The developed X-band SSPA is consists of 3-stage CSA(Corporate Structured Amplifier) modules in pre-amplifier stage, driver-amplifier stage and main-power amplifier stage. The main-power amplifier stage of SSPA designed by balanced type using GaN HEMT with enough power and gain to generate power more than 200-Watts in X-band. The developed SSPA has performance with more than total gain 59dB and output power 200-Watts in condition of frequency range 9.2-9.6GHz, pulse period 1msec, pulse width 100usec and duty cycle 10%. The developed SSPA in this paper can apply to high quality solid state radar system with pulse compression technique.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1313-1321
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• 2008

outphasing class-E power amplifier using composite right/left-handed transmission lines(CRLH-TL) is proposed at 2.4 GHz. The power combiner including CRLH-TL is designed to suppress the second and third harmonics to increase linearity and the output problem of the conventional outphasing amplifier is also solved by the proposed outphasing amplifier. So the P AE is improved. The measured maximum output power at the fundamental frequency shows 31.8 dBm, whereas the PAE shows 50 % with 14 dBm input power excited. The IMD3 is improved by 5 dB compared to that of conventional outphasing amplifier.

• Journal of Navigation and Port Research
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• v.26 no.2
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• pp.215-220
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• 2002

In this paper, the 100 watt unit ower amplifier using temperature independent biasing for DTV (Digital Television) repeater application is designed and fabricated. The DC operation point of this unit power amplifier at temperature variation from $20^{\circ}C$ to $100^{\circ}C$ is fixed by active bias circuit. The variation of current consumption in the 100 watt unit power amplifier has an excellent characteristics of less than 0.6A. The implemented unit power amplifier has the gain over 12dB, the gain flatness of less than 0.5dB and input and output return, loss of than 15dB over the DTV repeater frequency range (470~806MHz). This unit power amplifier yields intermodulation distortion(IMD) of more than 32dBc at 2MHz offset, which satisfies the IMD at output power of 100 watt (50dBm).

• 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 the Korea institute of electronic communication sciences
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• v.10 no.8
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• pp.945-952
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• 2015

Power amplification device which is matched to $50{\Omega}$ in order to achieve a high efficiency of a power amplifier using a GaN power amplification device, since there is a limit of application frequency bands, output power, efficiency characteristics selection, in this study based on the measurement data through the source/load-pull test, high output power and to extract quantitative input and output impedance that matches the design objectives of high output power, high efficiency, an implementation of the high efficiency power amplifier. Implemented power amplifier is shows 25watt(44dBm), PAE of 66-76% characteristics in the frequency band of 2.7-3.1 GHz.