• Title/Summary/Keyword: Amplitude/Phase Imbalance

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Useful Characteristics for Controlling the Cancellation Performance and Center Frequency of a Linearization Loop

  • Kang, Sang-Gee;Hong, Sung-Yong
    • ETRI Journal
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    • v.28 no.2
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    • pp.231-234
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    • 2006
  • The cancellation performance of a linearization loop is limited by the degree of an amplitude imbalance and a phase imbalance. A delay mismatch causes a phase variation as a function of frequency. Therefore, the cancellation performance and linearization bandwidth are limited by a delay mismatch. The expression for the effects of an amplitude imbalance, a phase imbalance, and a delay mismatch on the characteristics of a linearization loop is derived and analyzed. The simulation results are compared with the results obtained by means of using a commercial simulation tool and the exact agreement is reported. The derived equation could be used in designing a linearization loop and predicting the cancellation performance of the linearization loop usefully. Some useful characteristics, known from the simulation results obtained by using the derived equation, of a linearization loop for designing and implementing feedforward amplifiers are described in detail.

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Derivation and Analysis of the BER Closed Form in the OFDM Communication System with IQ Imbalance

  • Hieu Nguyen Thanh;Kang Byung-Su;Lee Kwang-Chun;Ryu Heung-Gyoon
    • Journal of electromagnetic engineering and science
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    • v.6 no.3
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    • pp.182-188
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    • 2006
  • Orthogonal frequency division multiplexing(OFDM) is very useful for the wireless communication system. However, OFDM is very sensitive to the radio frequency impairments. One of the most important major impairments is the IQ imbalance between in-phase(l) and quadrature(Q) branches in the up and down-conversion. IQ imbalance can be divided into phase and amplitude imbalances. These imbalances make constellation of signal to expand and rotate. The performance of system is severely degraded. In this paper, a closed-form for the bit error probability of the OFDM signal in IQ imbalance environment is derived in terms of the function of phase and amplitude imbalance parameters. So, it will be convenient and useful to evaluate the performance of OFDM communication system with IQ imbalance. It is confirmed that computer simulation results closely match with the results of the analytical derivation. When phase imbalance $\varphi=20^{\circ}$, amplitude imbalance $\varepsilon=0.1$; 0.3; 0.4; 0.5, BER at $10^{-5}$ is severely degraded by 1.8 dB, 3.12 dB, 4.72, and 8.44 dB, respectively.

Design of Ring Hybrid Balun with Good Amplitude and Phase balance (진폭과 위상 특성이 우수한 링 하이브리드 발룬 설계)

  • Na Won;Cho Il-Hyun;Lee Moon-Que
    • 한국정보통신설비학회:학술대회논문집
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    • 2006.08a
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    • pp.175-178
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    • 2006
  • We present a ring hybrid balun with additional two ${\lambda}/4$ short stubs that offers excellent amplitude and phase balance performance. The phase difference which is essentially occurred in $180^{\circ}$ ring hybrid is compensated by a ${\lambda}/4$ short stub in one output port. To compensate the amplitude imbalance inherent in the ring hybrid, the series resistance will be added to the second stub which is connected to another output port. The measured balun shows that phase imbalance is less than $2.5^{\circ}$ and magnitude imbalance is less than 0.2dB over a 1.75-2.25 GHz.

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Current-Steered Active Balun with Phase Correction

  • Park, Ji An;Jin, Ho Jeong;Cho, Choon Sik
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.15 no.6
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    • pp.629-633
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    • 2015
  • An active balun using current steering for phase correction is presented. The proposed active balun is constructed with two different unit balun structures based on current steering to reduce phase and amplitude errors. This type of topology can be compared with the conventional phase and amplitude correction techniques which do not incorporate the current steering. Designed and fabricated active balun in $0.18{\mu}m$ CMOS process operates over 0.95 - 1.45 GHz band, showing input reflection coefficient under -15 dB, phase error of $11^{\circ}$ and gain error of 0.5 dB. Gain is measured to be 0.3 dB maximum and power consumption of 7.2 mW is measured.

Implementation of a coherent detector with minimum errors for radar receiver (최소 에러를 갖는 레이다 수신기용 동기 검파 회로의 구현)

  • 양진모;김세영;김선주;전병태
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.11
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    • pp.60-69
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    • 1996
  • In this study, when the coherent detector has been developed and manufactured in the receiver of radar system, we have suggested and realized the 'Frequecny-Feedback correction (FFC)' that extracts its errors affecting the performance of radar, such as amplitude imbalances (k), phase imbalance ($\varphi$) between channels and offset votlages and corrects them to improve radar performances. Applying the FFC proposed, we analyzed sthe properties of the coherent detector and compared its perfomances after and before correction procdure. After the correction sequence, the amplitude imbalance was improved upt o 2dB and the phase imbalance over 9$^{\circ}$. The image rejection ratio (IRR), one of the figures of merit of radar system, was made better above 9 dB after correcting the coherent detector which possessed 23 dB before.

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Performance Analysis of OFDM Communication System with the IQ Imbalance and Phase Noise (IQ Imbalance와 위상 잡음을 고려한 OFDM 통신 시스템의 성능 분석)

  • Kim, Sang-Kyun;Ryu, Heung-Gyoon;Kang, Byung-Su;Lee, Kwang-Chun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.7
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    • pp.757-765
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    • 2007
  • OFDM system is an excellent high speed transmission method but it is seriously sensitive to the phase noise and IQ imbalance. Therefore, in this paper, we analyze the communication performance of the OFDM communication system with IQ imbalance and phase noise. Phase noise's variance can be calculated by integral calculus of phase noise power spectrum. From simulation results, it can be shown that the BER performances show different change according to the phase noise variance and IQ imbalance amount. When amplitude imbalance is ${\varepsilon}$=0.2; 0.3; 0.4 and phase imbalance is ${\phi}=10^0$, and distribution of phase noise is ${\sigma}^2=0.012$, BER is degraded by 2.88 dB, 3.61 dB, 4.09 dB in $10^{-5}$ in the respect of the SNR penalty.

A study on wideband strip-line balun using a power divider and a phase converter (전력 분배기와 위상 변환기를 이용한 광대역 스트립라인 발룬에 관한 연구)

  • Lee, Chang-Seok;Park, Ung-Hee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.7
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    • pp.1160-1164
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    • 2008
  • This paper presents an wideband stripline balun. And, the proposed balun is composed of one power divider and two phase converters on stripline substrate. The target characteristics of the proposed balun is the combination loss of below -0.05 dB, an amplitude imbalance of ${\pm}0.5\;dB$ and a phase imbalance of $180{\pm}10$ degrees, with the reflection coefficient(S11) of below -10 dB over frequencies ranging from 500 to 1500 MHz. The fabricated balun occupies the area of $12(W){\times}220(L){\times}2.3(T)\;mm3$. Experimental measurement shows that the fabricated balun has an amplitude imbalance of ${\pm}0.7\;dB$, a phase imbalance of $180{\pm}8$ degrees and an insertion loss of about -2 dB with the reflection coefficient(S11) of below -10 dB over frequencies ranging from 500 to 1,500 MHz.

Estimation of I/Q Imbalance Parameters for Repeater using Direct Conversion RF with Low Pass Filter Mismatch (저역 통과 필터 불일치를 포함한 직접 변환 RF 중계기의 I/Q 불균형 파라미터 추정)

  • Yun, Seonhui;Lee, Kyuyong;Ahn, Jaemin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.2
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    • pp.18-26
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    • 2015
  • In this paper, we studied the method for analyzing and estimating the parameters that induce I/Q imbalance in the repeater using direct conversion RF. In repeater, amplitude, phase, and filter mismatch are generated in the receiving-end which converts RF signal to baseband signal. And amplitude and phase mismatch are generated in the transmitting-end which converts baseband signal to RF signal. Accordingly, we modeled the parameters that cause I/Q imbalance in the structure of the repeater in order, and proposed a feedback test structure from the transmitting-end to the receiving-end for estimating the corresponding parameters. By comparing the test transmitting signal and received signal, it is possible to estimate the I/Q imbalance parameters which occurred from mixed components of real and imaginary part. And it was confirmed that I/Q imbalance phenomenon has been properly compensated with estimated parameters at the direct conversion RF repeater.

Analysis on Spectral Regrowth of Bandwidth Expansion Module by Quadrature Modulation Error in Digital Chirp Generator (디지털 첩 발생기에서의 직교 변조 오차에 의한 대역 확장 모듈에서의 스펙트럴 재성장 분석)

  • Kim, Se-Young;Sung, Jin-Bong;Lee, Jong-Hwan;Yi, Dong-Woo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.7
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    • pp.761-768
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    • 2010
  • This paper presents an effective method to achieve the wideband waveform for high resolution SAR(Synthetic Aperture Radar) using the frequency multiplication technique. And also this paper analyzes the root causes for the spectral regrowth due to 3rd-order intermodulation in chirp bandwidth expansion scheme using quadrature modulator and frequency multipliers. The amplitude and phase imbalance requirement are defined based on the simulation results in terms of quadrature channel imbalance. This minimizes the degradation of range resolution, peak sidelobe ratio and integrated sidelobe ratio. The wideband chirp generator using the frequency multiplier and memory map scheme was manufactured and the compensation technique was presented to reduce the spectral regrowth of SAR waveform by minimizing the amplitude and phase imbalance. After I and Q channel imbalance adjustment, the carrier level reduces -28.7 dBm to -53.4 dBm. Chirp signal with 150 MHz bandwidth at S-band expands to 600 MHz bandwidth at X-band. The sidelobe levels are reduced by about 8 to 9 dB by compensating the amplitude balance between I and Q channels.

Analysis of the Cancellation Performance of a linearization loop

  • Kang, Sang-Gee;Yi, Hui-Min;Hong, Sung-Yong
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2003.11a
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    • pp.183-187
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    • 2003
  • The expression for the effects of an amplitude imbalance, a phase imbalance and a delay mismatch on the characteristics of a linearization loop in feedforward amplifiers is derived and analyzed. The simulation results are compared with the results obtained by means of using a commercial simulation tool and the exact agreement is reported.

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