Digital Compensation in IQ Modulators Using Adaptive FIR Filters

Lim, A.G.K.C.; Sreeram, Victor; Wang, Guoqing

doi:10.1109/tvt.2004.836934

Cited by 6 publications

(5 citation statements)

References 13 publications

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“…where 1 is the all-one vector and S I (n) and S Q (n) are the Toeplitz matrices of s I (n) and s Q (n), respectively. In (11) and (12), the vectors…”

Section: A Parallel Filter Design For Impairment Parameter Estimatiomentioning

confidence: 99%

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Self-Calibration of Joint RF Impairments in a Loopback Wideband Transceiver

Deng

Lee

et al. 2020

IEEE Access

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This research studied transmitter/receiver (TX/RX) wideband (WB) RF impairments, namely frequency-dependent, frequency-independent I/Q imbalances and DC I/Q offsets. A real-based parallel structure is proposed to estimate and calibrate TX/RX WB RF impairment factors. RX impairment estimation and compensation are performed first using a frequency offset BPSK training signal. Then, the TX impairments are calibrated using a QPSK training signal. The proposed methods exhibited the following successes. First, a commercial off-the-shelf (COTS) AD9371 RF module with impairments was calibrated. After TX/RX calibration, the improvement of error vector measurement (EVM) of an OFDM 64QAM test signal was approximately 9.42 dB. Second, for the Taiwan Industrial Technology Research Institute's WB RF module with impairments, the EVM of an OFDM 16QAM test signal was calibrated and increased by about 20 dB. In summary, the proposed techniques can overcome WB RF impairments and enable high-quality WB communication. INDEX TERMS Calibration procedures, DC I/Q offsets, frequency-dependent I/Q imbalance, frequency-independent I/Q imbalance, RF impairment. I. INTRODUCTION Direct up/down RF chipsets are commonly used in wideband (WB) communication systems such as the 5G mobile communication system and digital video broadcasting systems. These chipsets have advantages such as low cost, simple design, and small area. However, for direct up/down conversion, multiple RF chips and oscillation circuits induce the different impairments including I/Q imbalance, DC offset, transmitter and receiver nonlinearities, phase noise, and coupling effects. In these impairments, many studies have extensively discussed I/Q imbalance. WB communication systems incur two I/Q imbalance effects: frequency-independent and frequency-dependent I/Q imbalances. Specifically, RF local oscillators generate I and Q carriers with amplitude and phase imbalance effects, resulting in so-called frequency-independent I/Q imbalance. In WB systems, the I and Q channels have the different impulse response effects and exhibit frequency-selective distortion, which is called frequency-dependent I/Q imbalance. The associate editor coordinating the review of this manuscript and approving it for publication was Nagendra Prasad Pathak.

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“…where 1 is the all-one vector and S I (n) and S Q (n) are the Toeplitz matrices of s I (n) and s Q (n), respectively. In (11) and (12), the vectors…”

Section: A Parallel Filter Design For Impairment Parameter Estimatiomentioning

confidence: 99%

“…In [10], Cavers et al proposed an adaptive compensation technique for quadrature modulation of TX RF. Lim et al [11] proposed digital adaptive algorithms and used two finite impulse response filters to compensate for the gain and phase of I/Q modulators. Moreover, numerous studies have proposed digital preprocessing methods.…”

mentioning

confidence: 99%

Self-Calibration of Joint RF Impairments in a Loopback Wideband Transceiver

Deng

Lee

et al. 2020

IEEE Access

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“…In the past, tuning for specific performance metrics such as IQ mismatch have been developed [6][7][8][9]. These are not suitable for concurrently tuning and trading off multiple device specifications.…”

Section: Bist For Computing Multiple Performance Metrics Of Rf Circuitsmentioning

confidence: 99%

BIST-assisted power aware self healing RF circuits

Devarakond

Natarajan

Sen

et al. 2009

2009 IEEE 15th International Mixed-Signals, Sensors, and Systems Test Workshop

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In this paper, a novel methodology for post manufacture tuning of RF circuits is presented. The procedure uses an iterative test-tune-test algorithm that applies a compact alternative test to the DUT and modulates circuit level tuning knobs (bias/supply values) based on the DUT specification values predicted from the test. The test procedure is repeated until convergence to the desired spec values is achieved with minimal impact on circuit power consumption. A key benefit of this approach is that tuning of multiple specifications can be performed concurrently due to the use of the alternative test methodology allowing upto 10X savings in test/tuning time.

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“…As a result, its predistorter is implemented by some memoryless models [110][111][112][113][114]. With the wideband signals in modern communication systems, TX IQ imbalance distortion shows significant memory effects (frequency-dependent), and is modeled (or predistorted) by some linear memory system [115][116][117]. In [117], the TX IQ imbalance are modeled by four parallel linear filters passing or crossing I and Q-paths, as illustrated in Fig The advantage of predistortion is that since it is implemented in digital baseband domain before the DAC, the TX IQ imbalance predistorter can be easily implemented either in microprocessor, or integrated circuits (IC).…”

Section: Fig 2-10 Tx Iq Imbalance Predistortionmentioning

confidence: 99%

“…Then define the frequency response of the mirror signal ( Fig. 5-2 shows the classical time-domain frequency-selective TX IQ imbalance predistortion scheme [115][116][117]. Fig.…”

Section: Iq Imbalance In Frequency Domainmentioning

confidence: 99%

Behavioral model on transmitter power amplifier and IQ imbalance

Fu¹

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This thesis is dedicated to the subject of the behavioral model of two most important analog impairments in modern wireless transmittersin-phase/quadrature (IQ) imbalance distortion and power amplifier (PA) nonlinear memory distortion. Despite their distinct physical characteristics, and unlike conventional ways of treating them differently and separately, this thesis is to treat these two seemingly different distortions equally and model them uniformly. Specifically, the main research efforts have gone through the following two stages: In the first stage, these two distortions are treated equally while independently, and compensated using the same methodologydigital predistortion. In this stage, the main objective is to find a better behavioral model for each distortion. Then in the next stage, these two distortions are merged as one black box, and characterized by a single behavioral model. The objective of this stage is to unify the view of the two distortions, abstract it in the implementation, and save the resources by unifying and simplifying the model. After the introduction chapter, the background of the two analog distortionstransmitter (TX) in-phase/quadrature imbalance and power amplifierare presented, followed by the general discussion of system-level simulation and digital predistortion, where the quality of the behavioral model determines both performances. Then a comprehensive literature review is engaged on the subjects of transmitter in-phase/quadrature Imbalance and power amplifier, from where it is clear that the current available behavioral models cannot satisfy the demanding requirements, and hence efforts are necessary to find a better, simpler, more accurate, while free-of-side-effects model.

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Digital Compensation in IQ Modulators Using Adaptive FIR Filters

Cited by 6 publications

References 13 publications

Self-Calibration of Joint RF Impairments in a Loopback Wideband Transceiver

Self-Calibration of Joint RF Impairments in a Loopback Wideband Transceiver

BIST-assisted power aware self healing RF circuits

Behavioral model on transmitter power amplifier and IQ imbalance

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