• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
• /
• pp.187-190
• /
• 2000

In this paper, A Feedforward Linear Power Amplifier which is appended a feedback loop for IMT-2000 was designed and fabricated. Feedback loop was used to improve the IMD(Inter-Modulation Distortion) characteristics of the main amplifier. And it is easy to cancel IMD on the min path and control IMD cancellation loop, compared with basic Feedforward Linear Power Amplifier. This feedback loop has the same effect of the Predistroter. So, This power amplifier was improved in IMD characteristics to add the effect of Predistroter to basic Feedforward amplifier. And the disigned power amplifier in this paper represented the 40dBm(10W) output and -55dBc 3rd IMD at center frequency 2.14GHz (@10MHz).

• 한국정보통신학회논문지
• /
• 제10권11호
• /
• pp.1934-1939
• /
• 2006

현재의 디지털 통신 시스템은 매우 다양한 디지털 변조 방식을 채택하고 있다. 이러한 통신 시스템에서는 인접 채널에 대한 간섭을 최대한 줄이기 위해서 필연적으로 선형 전력증폭기를 요하며 동시에 높은 효율의 전력증폭기가 요구된다. 본 논문에서는 선형성 및 효율이 동시에 개선되는 방식의 Doherty전력 증폭기를 시뮬레이션 최적화 기법을 통해 설계하고 동시에 시뮬레이션을 통해 설계한 평형 전력 증폭기의 결과와 비교하여 효율이 20% 선형성이 10dB 개선됨을 보였다.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제11권4호
• /
• pp.336-343
• /
• 2011

This paper introduces a simple variable gain amplifier (VGA) structure that shows an inherently dB-linear gain control property. Requiring no additional components for dB-linear control, the structure is compact and power efficient. The designed two-stage VGA shows a gain control range of 60dB with the gain error in the range of ${\pm}0.4$ dB. The power consumption including the output buffer is 20.4 mW from 1.2 V supply voltage with bandwidth of 630 MHz. The prototype was fabricated in a 0.13 ${\mu}m$ CMOS process and the VGA core occupies 0.06 $mm^2$.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 하계종합학술대회논문집
• /
• pp.110-113
• /
• 1998

An analysis of the relationship between a linear amplifier chain and an analog-to-digital converter(ADC) in a digital microwave widevand receiver, with respect to sensitivity and dynamic range issues, is presented. The effects of gain, third-order intermodulation products and ADC characteristics on the performance of the receiver are illustrated and design criteria for the linear amplifier chain given a specified ADC are developed. A computer program is used to calculate theretical receiver performance based on gain and third-order intermodulation product selections. Simulated results are also presented and compared with theoretical values.

• 전자공학회논문지D
• /
• 제34D권11호
• /
• pp.1-8
• /
• 1997

In this paper, we propose a new method for the improvement of linearizing and adaptive convergence charateristics of the feedforward linear power amplifier. In this circuit, errors at the signal cancellation stage can be compensated at the error cancellation stage and the overall linearizaton and adaptation characteristics of the linear amplifier are improved. The broadband characteristics and linearizing capability are improved without increasing the complexity of circuits and the signal processing structure.

• ETRI Journal
• /
• 제29권4호
• /
• pp.536-538
• /
• 2007

We propose and describe the fabrication of a linear power amplifier (LPA) using a new analog feedforward method for the IMT-2000 frequency band (2,110-2,170 MHz). The proposed analog feedforward circuit, which operates without a pilot tone or a microprocessor, is a small and simple structure. When the output power of the fabricated LPA is about 44 dBm for a two-tone input signal in the IMT-2000 frequency band, the magnitude of the intermodulation signals is below -60 dBc and the power efficiency is about 7%. In comparison to the fabricated main amplifier, the magnitude of the third intermodulation signal decreases over 24 dB in the IMT-2000 frequency band.

• Current Optics and Photonics
• /
• 제7권1호
• /
• pp.33-37
• /
• 2023

Real-time adaptive control of laser output polarization is presented in a 10-W-level non-polarization-maintaining (non-PM) fiber amplifier. While the output polarization from a non-PM fiber amplifier tends to be irregular, depending on output power, time, and perturbation, closed-loop polarization control can maintain the polarization extinction ratio at higher than 20 dB. Real-time polarization control can attain the target linear polarization mostly within 1.4-25 ms and shows stability against external perturbations. This approach can satisfy both linear polarization and high output power in a non-PM amplifier, and facilitates optimization of laser performance and maintenance-free operation.

• 한국전자파학회논문지
• /
• 제18권11호
• /
• pp.1262-1270
• /
• 2007

본 논문에서는 feedforward와 post-distortion 기법을 이용하여 평형 증폭기 내에서 발생하는 혼변조 왜곡 성분을 제거할 수 있는 새로운 왜곡 상쇄 메커니즘인 cross post-distortion 선형화 기법을 제안한다. 출력 동적 영역과 대역폭 측면에서 제안하는 선형화 방식은 기존의 feedforward 방식에 뒤지지 않는 성능을 가지고 있으면서 상대적으로 높은 효율을 제공한다. 이론적 뒷받침을 위해 제안하는 시스템과 feedforward 방식의 전력 증폭기와 오차증폭기의 전력 용량을 비교 분석하였고, IMT-2000 대역에서 실제 구현을 통하여 이를 실험적으로 뒷받침하였다. 최대 출력 전력 240 W의 기지국용 상용 대전력 증폭기에 적용했을 때, wideband code division multiple access (WCDMA) 4FA 신호에 대하여 평균 출력 전력 40 dBm에서 약 18.6 dB의 개선 효과를 얻었다. 제작된 전력 증폭기는 WCDMA 신호 기준으로 feedforward 방식에 비해 약 2 % 개선된 효율을 보였다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제30권4호
• /
• pp.505-513
• /
• 2006

A linear power amplifier is particularly emphasized on the system using a linear modulations, such as 16QAM and QPSK with pulse shaping. because intermodulation distortion which causes adjacent channel interference and co-channel interference is mostly generated in a nonlinear power amplifier. In this paper, parameters of a linearization loop, such as an amplitude imbalance a phase imbalance and a delay mismatch, are briefly analyzed to get a specific cancellation performance and linearization bandwidth. Experimental results are presented for IMT-2000 frequency band. The center frequency of the feedforward amplifier is 2140 MHz with 60 MHz bandwidth. When the average output power of feedforward amplifier is 20 Watt. the intermodulation cancellation performance is more than 21 dB. In this case, the output power of feedforward amplifier reduced 3.5 dB because of extra delay line loss and coupling loss. The feedforward amplifier efficiency is more than 7.2 % for multicarrier signals, 59 dBc for ACPR.

• 대한전자공학회논문지TC
• /
• 제42권2호
• /
• pp.81-86
• /
• 2005

본 논문에서는 PBG 구조를 이용하여 Doherty 증폭기의 선형성을 개선하였다. PBG 구조를 출력 정합회로에 구현하였으며, Doherty 증폭기의 호율 뿐 아니라 선형성을 개선 할 수 있었다. 제안된 PBG 구조를 이용한 Doherty 증폭기는 PAE $36.4\%$, IMD -24.5 dBc 였으며, IMD 측면에서 3 dBc, PAE 측면에서 약 $3\%$ 정도 개선되었다.