• Journal of Navigation and Port Research
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• v.26 no.3
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• pp.295-302
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• 2002

Currently digital communication system adapt various digital modulation schemes. All these communication systems are required to cause the minimum interference to adjacent channels, they must therefore employ the linear power amplifiers. In respect to linear power amplifiers, there are many linearization techniques. Feedforward power amplifier represent very wide bandwidth and high linearization capability. In the feedforward systems overall efficiency is reduced due to the loss of delay line. In this paper, delay filter instead of transmission delay line adapted to get more high efficiency. Experimental results showed that ACLR has improved 17.04dB which is added 2.54dB by using the delay filter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.10
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• pp.1518-1526
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• 1993

It has been known that the amplifiers for high power signal in satellite communication channels suffer from nonlinear distortions, which reduce the performance of the communication channel significantly. In order to compensate the nonlinear distortion, a new data predistortion method with the LMS algorithm is proposed in this paper, Whereas the previous approach handles this problem by assigning corresponding predistorter to each symbol for the case of 16-QAM, the proposed approach uses the same memory for the symbols, which have identical amplitudes, and predistors the input of high-power amplifiers by the amplitude and phase differences, resulting in better adaptive data predistorter with small number of digital memory (3 predistorters) and fast convergence rate. Superiority of the proposed approach in the paper is demonstrated by comparing it with the previous approach.

• 전기의세계
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• v.31 no.5
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• pp.383-390
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• 1982

The high power glass laser system was designed and constracted which consisted of a TEM$\_$00/ mode Q-switching oscillator, a pulse shaping, system, two-stage pre-amplifiers, five-stage main amplifiers, a Faraday rotator, and a uni-guide slit. The laser output of 3OGW with the pulsewidth of 2 nsec was obtained by performing the amplifiing experiment in this system. When the laser light with the pulsewidth of 10 nsec was amplified, the large factor of amplification was obtained in the beginning of pulse, but the factor of amplification decreased gradually in the later part of pulse. Therefore, the laser light which has short pulsewidth of-2nsec must be amplified in order to obtain the larger factor of amplification. When the laser beam from the high power glass laser system was irradiated to plasma, the reflected laser light from plasma which occured inevitably could be attenuated to the order of 10$\^$-4/ by using the Faraday rotator and the uni-guide slit.

• Journal of Sensor Science and Technology
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• v.6 no.2
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• pp.145-154
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• 1997

Based on a new search strategy using circuit simulation and simulated annealing with local search, a technique for design automation of high-performance operational amplifiers is proposed. For arbitrary circuit topology and performance specifications, through discrete optimization of a cost function with discrete design variables the design of operational amplifiers is performed. A special-purpose circuit simulator and some heuristics are used to reduce the design time. Through the design of a low-power high-speed fully differential CMOS operational amplifier usable in smart sensors and 10-b 25-MS/s pipelined A/D converters, it has been demonstrated that a design tool developed using the proposed technique can be used for designing high-performance operational amplifiers with less design knowledge and less design effort.

• Electronics and Telecommunications Trends
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• v.37 no.5
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• pp.11-21
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• 2022

GaN (Gallium-Nitride) is a promising candidate material in various radio frequency applications due to its inherent properties including wide bandgap, high carrier concentration, and high electron mobility/saturation velocity. Notably, AlGaN/GaN heterostructure field effect transistor exhibits high operating voltage and high power-density/power at high frequency. In next-generation radar systems, GaN power transistors and monolithic microwave integrated circuits (MMICs) are significant components of transmitting and receiving modules. In this paper, we introduce technological trends for C-/X-/Ku-band GaN MMICs including power amplifiers, low noise amplifiers and switch MMICs, focusing on the status of GaN MMIC fabrication technology and GaN foundry service. Additionally, we review the research for the localization of C-/X-/Ku-band GaN MMICs using in-house GaN transistor and MMIC fabrication technology. We also discuss the results of C-/X-/Ku-band GaN MMICs developed at Defense Materials and Components Convergence Research Department in ETRI.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.251-257
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• 2014

An actuator system is a type of motor designed to control a mechanism operated by a source of energy, in the form of an electric current by converting energy into some kind of motion. As audio actuators, transforming electric voltage signal into audio signal, speakers and amplifiers are commonly used. In applications of industry, high output power systems are required. For these systems to generate high-quality output, it is essential to control output impedance of audio systems. We have developed an adaptable power supply for driving active amplifier systems with variable loads. Depending on the changing values of resistance of the speaker which produces audible sound by transforming electric voltage signal, the power supply source of the active amplifier can generate the maximum power delivered to the speaker by an adaptable change of loads. The amplifier is well protected from the abrupt increment of peak current and an excess of current flow.

• Journal of Sensor Science and Technology
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• v.33 no.1
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• pp.12-17
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• 2024

Floating inverter amplifiers (FIAs) have recently garnered considerable attention owing to their high energy efficiency and inherent resilience to input common-mode voltages and process-voltage-temperature variations. Since the voltage gain of a simple FIA is low, it is typically cascaded or cascoded to achieve a higher voltage gain. However, cascading poses stability concerns in closed-loop applications, while cascoding limits the output swing. This study introduces a gain-enhanced FIA that features cross-coupled body biasing. Through simulations, it is demonstrated that the proposed FIA designed using a 28-nm complementary metal-oxide-semiconductor technology with a 1-V power supply can achieve a high voltage gain (> 90 dB) suitable for dynamic open-loop applications. The proposed FIA can also be used as a closed-loop amplifier by adjusting the amount of positive feedback due to the cross-coupled body biasing. The capability of achieving a high gain with minimum-length devices makes the proposed FIA a promising candidate for low-power, high-speed sensor interface systems.

• Journal of Advanced Navigation Technology
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• v.22 no.4
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• pp.319-324
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• 2018

In this paper, a high power amplifier using RF power solid-state semiconductor is implemented to overcome a problem of plasma generator which has the low efficiency, short life span, the difficult maintenance and the high-operation cost. This power amplifier consists of a radial combiner of low-loss and high power operation and the sixteen 300 W power amplifiers to obtain 3 kW output power for high power operation implemented in semiconductors at industrial scientific medical (ISM) band of 2.45 GHz. In addition, this amplifier overcomes the problem of heat generation due to high power by applying a water-cooled structure to the individual amplifiers. This power amplifier, which is made up of a small system, achieves 50% efficiency at the desired output.

• ETRI Journal
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• v.25 no.3
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• pp.195-202
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• 2003

This paper proposes a new LDMOSFET structure with a trenched sinker for high-power RF amplifiers. Using a low-temperature, deep-trench technology, we succeeded in drastically shrinking the sinker area to one-third the size of the conventional diffusion-type structure. The RF performance of the proposed device with a channel width of 5 mm showed a small signal gain of 16.5 dB and a maximum peak power of 32 dBm with a power-added efficiency of 25% at 2 GHz. Furthermore, the trench sinker, which was applied to the guard ring to suppress coupling between inductors, showed an excellent blocking performance below -40 dB at a frequency of up to 20 GHz. These results confirm that the proposed trenched sinker should be an effective technology both as a compact sinker for RF power devices and as a guard ring against coupling.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.2
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• pp.18-23
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• 1992

Recently, SSPAs(Solid-State Power Amplifiers) with high linearity and efficiency replace TWTAs (Traveling-Wave-Tube Amplifiers) in satellite transponders. In this paper, a power amplifier with maximum output power is designed and constructed using GaAs FET(MGF-1302) as a test model for the development of SSPAs. For conjugate matching of input and output network, transimission lines and stubs are optimized using microwave CAD program, LINMIC+. Power amplifier is realized on the teflon substrate($\in$S1rT=2.45) with a bandwidth of 1GHz at a center frequency of 8GHz. Maximum stable gain of simulation and simulation and experimental result is obtained 9.23, 7.65 dB, respectively.