A fully integrated 13 GHz CMOS SOI stacked power amplifier for 5G wireless systems

2019 16th International Symposium on Wireless Communication Systems (ISWCS)

Pärssinen

et al. 2019

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We study the impact of amplitude and phase differences between the parallel power amplifier (PA) branches in a phased array and their impact on the performance of the digital predistortion (DPD). The DPD coefficients are estimated from the array response in the far-field. The DPD coefficients need to be updated for changes in the nonlinear behavior of the PAs due to amplitude and phase variations. We present a training mechanism which makes the DPD robust to branch specific amplitude and phase weights and can tolerate these variations without the need of adapting to individual changes in the nonlinear behavior of the PA branches. The DPD is trained for a set of random amplitude and phase weights following normal distribution and the resultant mean DPD coefficients are used for predistortion. The simulation results show that the mean DPD can achieve the same average linearity performance as the continuously trained reference DPD for 32 elements uniform array.

Section: Array Dpd Setup Under Random Amplitude and Phase Variatmentioning

confidence: 99%

Average Linearization of Phased Array Transmitters Under Random Amplitude and Phase Variations

Khan

2019 16th International Symposium on Wireless Communication Systems (ISWCS)

Pärssinen

et al. 2019

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“…The array has M A parallel antennas and PAs. In the simulations, we use a memoryless look-up table (LUT) PA model extracted from amplitude to amplitude modulation (AMAM) and amplitude to phase modulation (AMPM) measurements of a 13 GHz, 45-nm, 4-stack complementary metal oxide semiconductor (CMOS) silicon on insulator (SOI) PA [14]. The PA simulation model is presented in Fig.…”

Section: Statistical Dpd Architecture For Phased Array a Overviementioning

confidence: 99%

Statistical Linearization of Phased Arrays Using Power Adaptive Power Amplifier Model

Khan

2019 IEEE 30th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

Pärssinen

et al. 2019

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Phased arrays used in millimeter-wave systems challenge the concept of power amplifier (PA) linearization by digital predistortion (DPD). This is due to the shared digital path and inaccuracies in analog beamforming and other component variations. However, the group behavior of multiple parallel nonlinear branches can be expected to be more predictable due to averaging effect compared to a single branch behavior. In this paper, we use a power adaptive nonlinear model to mimic the average behavior of a single PA and utilize the probability distribution of the input power of each individual PA to approximate the expected nonlinear behavior of the array over-the-air. The approximated array response is used for the DPD training. The simulation results indicate that the proposed approach provides good linearization performance for large arrays that have varying amplitude and phase weights.

“…The transitions between the frequency and time domain models are calculated by using Discrete Fourier Transform (DFT). The PA model is a lookup table which is based on the AMAM & AMPM measurements of the 13 GHz 4-stack 45nm CMOS SOI PA [11]. The input waveform is 100 MHz The analysis is divided into three parts.…”

Section: A Pa Array Model and Simulation Parametersmentioning

confidence: 99%

Analyzing the Effects of PA Variations on the Performance of Phased Array Digital Predistortion

2018 IEEE 29th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

Leinonen

Aikio

et al. 2018

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This paper shows how digital predistortion of a phased array can benefit from the parametric variations over parallel power amplifiers (PAs). Different antenna configurations are simulated by varying the PA input drive levels by the Monte-Carlo method. The error vector magnitude (EVM) at the steering angle and total radiated adjacent channel power ratio (TRACPR) are used as performance metrics. The simulation results indicate that array predistortion can benefit from the variations between the PAs to improve the EVM significantly. However, at the same time, the TRACPR performance is reduced. This gives a new trade-off to balance between in-band and outoff-band distortion in the fifth generation beamforming systems.