An IQ Image Cancellation Method for Digital-Intensive Transmitters

Markovic, J.; Hamidović, Damir; Mayer, Christian; Huemer, Mario; Springer, Andreas

doi:10.1109/iscas.2019.8702388

Cited by 6 publications

(8 citation statements)

References 12 publications

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“…5a It can be noticed that the edges of the LOs are shifted in time due to the phase difference between them. In most of RF-DAC-based architectures, the magnitude of an RF signal is updated with the rising and/or falling edges of the switching LO signal [24]. This means that magnitudes of the two MP components can be updated at different time instances, depending on the phases of currently used LOs.…”

Section: A Systematic Problem Analysismentioning

confidence: 99%

A Systematic Solution for the Problem of Spectral Degradation in Multiphase TX Architectures

Hamidović

Preyler

Preissl

et al. 2022

IEEE Trans. Circuits Syst. II

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With ever more stringent requirements of cellular standards it is an ongoing challenge to find the optimal RF transmitter architecture. In recent years, the multiphase transmitter (MP TX) architecture has been introduced as a promising candidate. It features high power efficiency and avoids phase modulation which is critical for upconversion of ultra-wideband signals. In this paper, the problem of unwanted spectral emission, inherent in MP TX architectures, is compensated by a proper data delay. Such an approach is considered for the first time in the multiphase architecture and achieves a spectral improvement of up to 38 dB in adjacent channels and 24 dB at the receiver (RX) duplex distance for a new radio (NR) signal with 20 MHz bandwidth. With the proposed solution the MP TX architecture becomes a highly competitive candidate for wideband signals such as LTE, LTE-CA or NR signals. In addition, a detailed and efficient implementation of the digital front-end (DFE) for the MP TX architecture including the proposed data delay is presented.

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Section: A Systematic Problem Analysismentioning

confidence: 99%

A Systematic Solution for the Problem of Spectral Degradation in Multiphase TX Architectures

Hamidović

Preyler

Preissl

et al. 2022

IEEE Trans. Circuits Syst. II

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“…Quadrature-based capacitive RF-DAC architectures additionally suffer from mismatches between in-phase and quadrature-related cells, causing an undesired IQ image in the output spectrum of the RF-DAC. The detailed analysis and a cancellation technique have been proposed by Markovic et al [29]. Polar architectures, on the other hand, suffer from bandwidth expansion of the required magnitude and phase modulation, degrading the ACPR especially for wideband input signals [35].…”

Section: A Nonidealities Of Capacitive Rf-dacsmentioning

confidence: 99%

“…DPD concepts targeting specific nonlinear effects of capacitive RF-DACs have been proposed by This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ Markovic et al [28], [29]. The resulting mathematical models are based on the detailed analysis of the origin and the resulting effects of the nonlinearities of the RF-DAC design, resulting in low complexity, but powerful DPD approaches.…”

mentioning

confidence: 99%

A Circuit-Inspired Digital Predistortion of Supply Network Effects for Capacitive RF-DACs

Trampitsch

Kalcher²,

Enzinger³

et al. 2021

IEEE Trans. Microwave Theory Techn.

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This article presents a novel digital predistortion (DPD) approach to compensate for nonlinear dynamic distortions caused by the supply network of capacitive radio frequency digital-to-analog converters (RF-DACs). The developed DPD concept recreates the voltage distortion on the RF-DAC's supply network and modulates the input signal such that the effects on the output signal of the RF-DAC are canceled. In contrast to conventional DPD approaches such as pruned Volterra series or memory polynomials, the complexity of the proposed concept is reduced to a feasible level, allowing for implementation in integrated circuits. Furthermore, the derived DPD model allows to use linear estimation algorithms for coefficient training. The presented DPD is demonstrated by measurements of two different capacitive RF-DAC designs and compared with conventional DPD approaches. EVM and adjacent channel power ratio (ACPR) can be improved by up to 6 and 7 dB, respectively, outperforming conventional approaches. Index Terms-Digital predistortion (DPD), memory effects, memory polynomial (MP), power amplifier (PA), radio frequency digital-to-analog converter (RF-DAC), switched-capacitor power amplifier (SCPA), Volterra series. I. INTRODUCTION T HE demand for high data rates, robust transmissions, and power efficiency poses stringent requirements on the design of integrated wireless transceiver systems. Increasing the data rate, while simultaneously providing a reliable and power-efficient transmission, is closely related to the linearity of the communication systems. In radio frequency (RF) wireless communication transmitters, the key component in terms of linearity and Manuscript

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“…Now, (7) states that the ideal reference signal shows no outof-band noise and just consists of two Dirac pulses in the frequency domain, each one weighted differently depending on the angle φ. The reason to choose this baseband signal is, that it covers three different modulation types.…”

Section: Principle Limitations Of Digital Polar Transmittersmentioning

confidence: 99%

“…Those architectures achieve better results in terms of power consumption, voltage and temperature variations or power added efficiency (PAE), compared to mostly analog architectures [2]. In the last years different RF transmitter architectures have been published like all-digital-quadrature (IQ) [2]- [7], digital-polarbased [8], [9], multiphase [10], [11], outphasing [12]- [16] or hybrid IQ-polar architectures [17]. The application of digital switching for millimeter waves (mmWave) frequencies is challenging and implementations are not yet shown.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Spectral Degradation and Error Compensation in 5G NR Digital Polar Transmitters

Preissl

Preyler

Mayer

et al. 2020

IEEE Trans. Circuits Syst. I

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Cellular standards evolve to support increasingly higher bandwidths which results in strict in-and out-of-band requirements such as lower error vector magnitude (EVM) and/or adjacent channel leakage ratio (ACLR). Digital polar transmitters, which are showing the best performance in terms of power consumption, are challenged to fulfill these requirements. This work will show that even in case of ideal analog components and infinite digital resources, there are principle limitations in terms of out-of-band noise for digital polar transmitters. A typical polar modulation will be compared to a theoretical signal with continuous amplitude modulation. The analysis of the resulting error signal suggests a decomposition into two components which can be partially compensated in the amplitude and phase modulation paths. Based on that decomposition a compensation algorithm has been developed and evaluated with a 400 MHz 5G New Radio (NR) signal for Band n257 on Frequency Range 2 with carrier frequency of 26.5 GHz. The compensation results in an out-of-band noise reduction of 44 dB close to the carrier frequency. Furthermore, EVM improvements for NR signals are demonstrated.

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An IQ Image Cancellation Method for Digital-Intensive Transmitters

Cited by 6 publications

References 12 publications

A Systematic Solution for the Problem of Spectral Degradation in Multiphase TX Architectures

A Systematic Solution for the Problem of Spectral Degradation in Multiphase TX Architectures

A Circuit-Inspired Digital Predistortion of Supply Network Effects for Capacitive RF-DACs

Analysis of Spectral Degradation and Error Compensation in 5G NR Digital Polar Transmitters

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