Adaptive compensation for imbalance and offset losses in direct conversion transceivers

Cavers, J.K.; Liao, Mingxia

doi:10.1109/25.260752

Cited by 218 publications

(33 citation statements)

References 7 publications

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“…A drawback of this method is the rather large power consumption of the DACs and the mixer. The circuit also suffers from analog imperfections such as (frequency dependent) IQ imbalance, skew mismatch, and DC offset, which leads to images and carrier feedthrough if not properly compensated [1].…”

Section: Introductionmentioning

confidence: 99%

Predistortion of Digital RF PWM Signals Considering Conditional Memory

Seebacher

Singerl

Schuberth

et al. 2015

IEEE Trans. Circuits Syst. I

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The trend in transmitter systems is to move the digital domain closer towards the antenna using digital modulators and drivers to reduce circuit complexity and to save power. A common assumption made is that they are capable of generating ideal pulses and thus do not suffer from analog imperfections. But the output signals of real drivers for high frequency operation are not perfectly rectangular anymore, which leads to distortion lowering the signal quality. In this paper the general properties of high frequency digital driver circuits operating at 2.6 GHz are analyzed and the impact of the different effects is presented. The predistortion of such drivers in the context of digital discrete time RF PWM modulators is studied. It has been found that conventional sample based predistortion can only correct the driver nonlinearity from 29 dBc to 49 dBc for the example considered using a 40 MHz bandwidth signal at 2.6 GHz. Therefore a special predistortion scheme considering the impact of pulses adjacent to the other samples is proposed. The mitigation of effects due to the discrete time nature of the signal is considered and discussed in detail. The capabilities of the proposed predistortion scheme are verified by extensive simulations as well as by measurements. By applying the proposed predistortion concept the spectral quality can be further improved to 66 dBc. In addition different scenarios with limited resolution and a carrier frequency offset are analyzed.

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Section: Introductionmentioning

confidence: 99%

Predistortion of Digital RF PWM Signals Considering Conditional Memory

Seebacher

Singerl

Schuberth

et al. 2015

IEEE Trans. Circuits Syst. I

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“…A key requirement for tuning is that the test response must be maximally sensitive to process as well as tuning knob perturbations across the allowed ranges of tuning knob values and across multiple process corners. Prior Work in Calibration/Tuning: There has been significant work in the past on digital calibration techniques that compensate for nonlinearity in RF circuitry [15][16][17][18][19][20]. Digital calibration is performed through the use of a predistortion filter in the transmitter or a postdistortion filter in the receiver whose coefficients are calibrated via application of dedicated multitone tests or transmitted/received symbol measurements.…”

Section: Introductionmentioning

confidence: 99%

Accurate signature driven power conscious tuning of RF systems using hierarchical performance models

Banerjee

Sen

Devarakond

et al. 2011

2011 IEEE International Test Conference

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In this research, a new post-manufacture tuning approach for yield improvement of advanced RF systems is developed. The proposed method first determines module level performances from the system level response (signature) to an applied RF diagnostic test using top-down model diagnosis. Then a constrained optimizer is used to determine the best module level tuning parameter values that satisfy system level specifications (bottom-up analysis) based on the determined performances of the individual modules in a power-conscious manner. Both top-down and bottom-up analysis techniques are supported by hierarchical RF behavioral models. The health (effects of process variations) of individual modules affects the relationship between module level tuning parameters and module level performance metrics and is factored into the tuning procedure. A key benefit of the proposed approach is that only a single test application is needed. Simulation results and hardware data prove the efficiency of the proposed tuning technique.

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“…The latter distortion is due to phase and amplitude imbalances of the local oscillator (LO) and mismatch in the cascade of digital-analog converters (DAC)-low-pass filters in the I and Q branches. The effects of IQ imbalance on predistortion techniques have been presented in [5][6][7][8]. Joint PD and IQ compensation techniques have been previously considered in several studies for the SISO case [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Power amplifier linearization technique with IQ imbalance and crosstalk compensation for broadband MIMO-OFDM transmitters

Gregorio

Cousseau

Werner

et al. 2011

EURASIP J. Adv. Signal Process.

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The design of predistortion techniques for broadband multiple input multiple output-OFDM (MIMO-OFDM) systems raises several implementation challenges. First, the large bandwidth of the OFDM signal requires the introduction of memory effects in the PD model. In addition, it is usual to consider an imbalanced in-phase and quadrature (IQ) modulator to translate the predistorted baseband signal to RF. Furthermore, the coupling effects, which occur when the MIMO paths are implemented in the same reduced size chipset, cannot be avoided in MIMO transceivers structures. This study proposes a MIMO-PD system that linearizes the power amplifier response and compensates nonlinear crosstalk and IQ imbalance effects for each branch of the multiantenna system. Efficient recursive algorithms are presented to estimate the complete MIMO-PD coefficients. The algorithms avoid the high computational complexity in previous solutions based on least squares estimation. The performance of the proposed MIMO-PD structure is validated by simulations using a two-transmitter antenna MIMO system. Error vector magnitude and adjacent channel power ratio are evaluated showing significant improvement compared with conventional MIMO-PD systems.

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Adaptive compensation for imbalance and offset losses in direct conversion transceivers

Cited by 218 publications

References 7 publications

Predistortion of Digital RF PWM Signals Considering Conditional Memory

Predistortion of Digital RF PWM Signals Considering Conditional Memory

Accurate signature driven power conscious tuning of RF systems using hierarchical performance models

Power amplifier linearization technique with IQ imbalance and crosstalk compensation for broadband MIMO-OFDM transmitters

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