• ETRI Journal
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• v.24 no.2
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• pp.81-96
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• 2002

This paper describes our design of a hybrid amplifier composed of a distributed Raman amplifier and erbium-doped fiber amplifiers for C- and L-bands. We characterize the distributed Raman amplifier by numerical simulation based on the experimentally measured Raman gain coefficient of an ordinary single mode fiber transmission line. In single channel amplification, the crosstalk caused by double Rayleigh scattering was independent of signal input power and simply given as a function of the Raman gain. The double Rayleigh scattering induced power penalty was less than 0.1 dB after 1000 km if the on-off Raman gain was below 21 dB. For multiple channel amplification, using commercially available pump laser diodes and fiber components, we determined and optimized the conditions of three-wavelength Raman pumping for an amplification bandwidth of 32 nm for C-band and 34 nm for L-band. After analyzing the conventional erbium-doped fiber amplifier analysis in C-band, we estimated the performance of the hybrid amplifier for long haul optical transmission. Compared with erbium-doped fiber amplifiers, the optical signal-to-noise ratio was calculated to be higher by more than 3 dB in the optical link using the designed hybrid amplifier.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.602-607
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• 2006

In this paper, the distributed network synthesis, which is useful to the design of wireless power amplifiers, is proposed, and a RF power amplifier is designed using the technique. The transfer function of distributed matching circuits is derived by Chebyshev approximation, and network element values for a specified topology are given as a function of minimum insertion losses and ripples. As an example, after a power transistor is modeled by load-pull data, the synthesis for distributed matching networks is applied to a power amplifier design, which has the electrical performance of 17dB gain and less IM3 than -43dBc at the 20W output power between 800 to 900MHz frequency range. Experimental results from a fabricated amplifier are shown to approach the design performance in the operating frequency range. The design of impedance matching networks by the transfer function synthesis is a useful method for the design of RF power amplifiers.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.178-180
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• 2017

This study presents a 2-20 GHz monolithic distributed power amplifier (DPA) using a $0.25{\mu}m$ AlGaN/GaN on SiC high electron mobility transistor (HEMT) technology. The gate width of the HEMT was selected after considering the input capacitance of the unit cell that guarantees decade bandwidth. To achieve high output power using small transistors, a 12-stage DPA was designed with a non-uniform drain line impedance to provide optimal output power matching. The maximum operating frequency of the proposed DPA is above 20 GHz, which is higher than those of other DPAs manufactured with the same gate-length process. The measured output power and power-added efficiency of the DPA monolithic microwave integrated circuit (MMIC) are 35.3-38.6 dBm and 11.4%-31%, respectively, for 2-20 GHz.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.818-823
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• 2014

A high-gain wideband low noise amplifier (LNA) using $0.25-{\mu}m$ Gallium-Nitride (GaN) MMIC technology is presented. The LNA shows 8 GHz to 15 GHz operation by a distributed amplifier architecture and high gain with an additional common source amplifier as a mid-stage. The measurement results show a flat gain of $25.1{\pm}0.8dB$ and input and output matching of -12 dB for all targeted frequencies. The measured minimum noise figure is 2.8 dB at 12.6 GHz and below 3.6 dB across all frequencies. It consumes 98 mA with a 10-V supply. By adjusting the gate voltage of the mid-stage common source amplifier, the overall gain is controlled stably from 13 dB to 24 dB with no significant variations of the input and output matching.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.12
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• pp.7-12
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• 2004

In this paper, CPW wideband distributed amplifier was designed and fabricated using 0.1 $\mum$ InGaAs/InAlAs/GaAs Metamorphic HEMT(High Electron Mobility Transistor). The DC characteristics of MHEMT are 442 mA/mm of drain current density, 409 mS/mm of maximum transconductance. The current gain cut-off frequency(fT) is 140 GHz and the maximum oscillation frequency(fmax) is 447 GHz. The distributed amplifier was designed using 0.1 $\mum$ MHEMT and CPW technology. We designed the structure of CPW curve, tee and cross to analyze the discontinuity characteristics of the CPW line. The MIMIC circuit patterns were optimized electromagnetic field through momentum. The designed distributed amplifier was fabricated using our MIMIC standard process. The measured results show S21 gain of above 6 dB from DC to 45 GHz. Input reflection coefficient S11 of -10 dB, and output reflection coefficient S22 of -7 dB at 45 GHz, respectively. The chip size of the fabricated CPW distributed amplifier is 2.0 mm$\times$l.2 mm.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.5 no.1 s.9
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• pp.13-19
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• 2006

In this paper, a broadband Microwave Power Module(MPM) operating at 7 - 11 GHz is designed and fabricated. The MPM consists of a SSA (Solid State Amplifier) and a conventional TWT (traveling Wave Tube). This combined module takes advantage of a low noise and high gain of SSA. The computer modeling and simulation of the SSA are designed by the use of the ADS (Advanced Design System) software. The SSA is designed by configurating the CSSDA (Cascaded Single Stage Distributed Amplifier). The broadband MPM is measured to be noise figure 8.3 - 10.02 dB at 7 - 11 GHz bandwidth, output power of 38.12 dBm at 9 GHz.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.6
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• pp.42-50
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• 1984

The method of increasing the bandwidth of distributed amplifier by the feedback loop is presented in this paper. In this method, it is tried to increase the gain of the amplifier in the high frequency range by giving a positive feedback on the device, while giving no influence in the low frequency range. For the simplicity of the amplifier design the transmission line theory of periodical structure with a unilateral divice is used in the design, and the 2-ports cascade network theory developed by K.B. Niclas is used in computer analysis for the purpose of precise results. In this simulation, the bandwidth of the amplifier is increased from 16 [GHz] without feedback loop to about 20 [GHz] with the feedback loop.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.15-22
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• 2008

In this paper, we propose a numerical analysis on reversed current of distributed amplifier based on transmission line theory and proposed a theory to obtain optimum transmission line length to minimize the reversed currents by cancelling those components. The reversed current is analyzed as being simply absorbed into the terminal resistance in the conventional analysis. In the proposed analysis, however, they are designed to be cancelled by each other with opposite phase by the optimal length of the transmission lint Circuit simulation and implementation using pHEMT transistor were performed to validate the proposed theory with the cutoff frequency of 3.6 GHz. From the measurement, maximum gain of 14.5dB and minimum gain of 12.3dB were achieved In the operation band. Moreover, measured efficiency of the proposed distributed amplifier is 25.6% at 3 GHz, which is 7.6%, higher than the conventional distributed amplifier. Measured output power Is about 10.9dBm, achieving 1.7dB higher output power than the conventional one. Those improvement is thought to be based on the cancellation of refersed current.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.570-573
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• 2004

This paper present a distributed RC lines (URCs) oscillator with sinusoidal output. The frequency of oscillator can be controlled and adjustable by varying an one pole amplifier. The circuit incorporated an gain controller loop for amplitude stabilization with low distortion. The realization of simulation and experimental results are in reasonably good agreement with the theoretical , and very low harmonic distortion. In this circuit can be suitable for LSI process fabrication and the circuit application in electronic communications system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.681-689
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• 2010

We will demonstrate a novel topology for the feedforward amplifier. This amplifier does not use a delay element thus providing an efficiency enhancement and a size reduction by employing a distributed element negative group delay circuit. The insertion loss of the delay element in the conventional feedforward amplifier seriously degrades the efficiency. Usually, a high power co-axial cable or a delay line filter is utilized for a low loss, but the insertion loss, cost and size of the delay element still acts as a bottleneck. The proposed negative group delay circuit removes the necessity of the delay element required for a broadband signal suppression loop. With the fabricated 2-stage distributed element negative group delay circuit with -9 ns of total group delay, a 0.2 dB of insertion loss, and a 30 MHz of bandwidth for a wideband code division multiple access downlink band, the feedforward amplifier with the proposed topology experimentally achieved a 19.4 % power added efficiency and a -53.2 dBc adjacent channel leakage ratio with a 44 dBm average output power.