• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1529-1533
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• 2005

In this paper designed available pre-amplifier to Intrabroadband power amplifier. Designed pre-amplifier used WJ company's AMI which frequency characteristic and noise characteristic are superior. Designed to have superior VSWR characteristic and frequency characteristic covering broadband of 100MHz ${\~}$ 3GHz using feedback. Designed ye-amp broadband special qualify such as EMC measurement equipment roll important position do to utilize to power amplifier of equipment that how consider.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.62-66
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• 2006

본 논문은 도허티 증폭기 및 포락선 전치 왜곡기를 이용한 전력 증폭기의 효율 및 선형성 개선에 관한 것이다. 전력 증폭기의 효율을 개선하기 위하여 도허티 증폭기를 제작하여 효율 특성을 개선하였으며, 포락선 전치 왜곡기를 이용하여 도허티 증폭기의 선형성 개선량에 대하여 조사하였다. 제작된 도허티 증폭기는 AB 급으로 동작시킨 전력 증폭기와 비교하여 출력 전력 10W에서 8.5%의 효율 개선 효과를 보였으며, 출력 전력 40W에서 12.6%의 효율 개선 특성을 나타내었다. 포락선 전치 왜곡기를 이용한도 허티 증폭기는 출력 전력 10W에서 7dB의 선 형성 개선 효과를 나타내었다. IMT-2000 주파수 대역에서 WCDMA down-link 4 carrier 신호를 이용하여 출력 전력 10W에서 측정한 결과 AB 급으로 동작하는 전력 증폭기와 비교하여 4.2%의 효율 개선 및 6.3dB의 선형성 개선 효과를 나타내었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.485-488
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• 2005

In this paper designed available pre-amplifier to Ultrabroadband power amplifier. Designed pre-amplifier used WJ company's AM1 which frequency characteristic and noise characteristic are superior. Designed to have superior VSWR characteristic and frequency characteristic covering broadband of 100MHz ${\sim}$ 3GHz using feedback.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.180-181
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• 2001

이 논문은 채널당 1Gbps로 동작하는 10채널 광 수신기를 0.25$mu extrm{m}$ CMOS공정을 이용하여 설계한 것이다. 광 수신기는 크게 2부분으로 나눠지는데 첫 번째 부분은 입력된 전류 신호를 전압 신호로 변환시켜주는 역할을 하는 트랜스임피던스 전치증폭기이고, 다음 부분은 원하는 디지털 레벨로 풀스윙 할 수 있도록 하는 후치증폭기이다. 전치증폭기의 출력 전압은 스윙폭에 무관하게 그 다음 단에서 적당한 디지털 레벨 데이터로 변환되어야한다. (중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.11
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• pp.1071-1083
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• 1991

In this paper, we describe the design and realization of optical preamplifier with InGaAs APD and GaAs MESFET. Optical preamplifier which is three stage trans-impedance circuit is analyzed in detail and realized in microstrip circuits. With the kmowledge of the InGaAs, GaAs MESFET and BJT, the performance of the optical is predicted by computer simulation and the theoretical predictions are compared with the experimental results. The designed hybrid MIC optical preamplifier exhibits a bandwith of 380MHz and a receiver sensitivity of -40. 6dBm at $1.55{\mu}m$ wavelength when operating at 565Mb/s with BER of $10^{-9}$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.681-684
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• 2015

Power amplifier is an essential component for transmitting signals to a remote receiver in wireless communication systems. Power amplifier is a non-linear device in general, and the nonlinear distortion becomes severer as the output power increases. The nonlinearity results in spectral regrowth, which leads to adjacent channel interference, and decreases the transmit signal quality. To linearize power amplifiers, many techniques have been developed so far. Among the techniques, digital pre-distortion is known as the most cost and performance effective technique. However, the linearization performance falls down abruptly when the power amplifier operates in its saturation region. This is because of the severe nonlinearity. To relieve this problem, this paper proposes a new adaptive predistortion technique. The proposed technique controls the adaptive algorithm based on the power amplifier input level. Specifically, for small signals, the adaptive predistortion algorithm works normally. On the contrary, for large signals, the adaptive algorithm stops until small signals occur again. By doing this, wrong coefficient update by severe nonlinearity can be avoided. Computer simulation results show that the proposed method can improve the linearization performance compared with the conventional digital predistortion algorithms.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.8 s.338
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• pp.53-60
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• 2005

Recently, sub-micron CMOS technologies have taken the place of III-V materials in a number of areas in integrated circuit designs, in particular even for the applications of gjgabit optical communication applications due to its low cost, high integration level, low power dissipation, and short turn-around time characteristics. In this paper, a four-channel transimpedance amplifier (TIA) array is realized in a standard 0.35mm CMOS technology Each channel includes an optical PIN photodiode and a TIA incorporating the fully differential regulated cascode (RGC) input configuration to achieve effectively enhanced transconductance(gm) and also exploiting the inductive peaking technique to extend the bandwidth. Post-layout simulations show that each TIA demonstrates the mid-band transimpedance gain of 59.3dBW, the -3dB bandwidth of 2.45GHz for 0.5pF photodiode capacitance, and the average noise current spectral density of 18.4pA/sqrt(Hz). The TIA array dissipates 92mw p in total from a single 3.3V supply The four-channel RGC TIA array is suitable for low-power, high-speed optical interconnect applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.673-676
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• 2015

Digital Pre-Distortion (DPD) is a linearization technique for nonlinear power amplifiers (PAs) by implementing inverse function of the PA at baseband digital stage. To obtain proper DPD parameters, a feedback path is required to convert the PA output to a baseband signal, and a memory is also needed to store the feedback signals. DPD parameters are usually found by an adaptive algorithm from the feedback samples. However, for the adaptive algorithm to converge to a reliable solution, long feedback samples are required, which increases convergence time and hardware complexity. In this paper, we propose a DPD technique that requires relatively short feedback samples. From the observation that the convergence time of the adaptive algorithm highly depends on the initial condition, this paper iteratively utilizes the feedback samples while keeping and using the converged DPD parameters at the former iteration as the initial condition at the current iteration. Computer simulation results show that the proposed method performs better than the conventional technique while the former requires much shorter feedback samples than the latter.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.219-225
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• 2012

A low-power, low-noise pre-amplifier for digital hearing-aid application is designed. This pre-amplifier amplifies single-ended signal from an electret microphone, and produces differential output to be delivered to an ADC. It has a variable gain of 3.6, 7.2, 14.4 and 28.8 with a bandwidth between 100Hz~10kHzon. The measurement results show 85 dB of SNR, 0.05 % of harmonic distortion and $200{\mu}W$ of power consumption with 1.2V supply.

• ETRI Journal
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• v.8 no.3
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• pp.109-122
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• 1986

본고에서는 광수신기 전치 증폭기의 종류에 따른 장단점을 설명하였고, 지금까지 발표된 전치 증폭기의 configuration들과 잡음 특성들을 고찰하였다. 그리고 최근의 광수신기에 대한 연구 동향을 살피는 한편, 앞으로 해야할 연구 방향을 제시하였다.