A Nonlinear Switched State-Space Model for Capacitive RF DACs

Trampitsch, Stefan; Markovic, J.; Obmann, Patrick; Fritzin, Jonas; Mayer, Christian; Fulde, M.; Pretl, Harald; Springer, Andreas; Huemer, Mario

doi:10.1109/tcsi.2017.2666773

Cited by 15 publications

(9 citation statements)

References 17 publications

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“…LOs are simply scaled with the magnitude-values for each LO-cycle and summed up resulting in an output RF signal. The LO generation and mixing with data in the RF-DAC is simulated ideally, omitting the impact of phase noise [21], [22] and RF-DAC nonlinearity [23]. The focus is to emphasize the systematic problem of OOB spectral emission, discussed later in this section.…”

Section: Multiphase Tx Working Principlementioning

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: Multiphase Tx Working Principlementioning

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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“…The output voltage of the unloaded capacitive RF-DAC, decomposed into a Fourier series, and assuming infinitely steep signal transitions, is given by [33] v…”

Section: Capacitive Rf-dacmentioning

confidence: 99%

“…Another origin of nonlinear effects results from the mismatch of the respective pMOS and nMOS ON-resistances of the driving inverters in each switching cell. Unequal ON-resistances change the charging and discharging time constant of the cell array, resulting in a code-dependent modulation of the output phase, causing AM-PM distortion [18], [33].…”

Section: A Nonidealities Of Capacitive Rf-dacsmentioning

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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“…Among the published architectures and CMOS implementations, which are evolving quickly, digital-polar-, digital-quadrature-and pulse-encoding-based switched-mode transmitter systems are most commonly found and have been proven feasible for wireless communications [8,9]. Pulse encoding approaches generally require additional high-Q filtering after RF signal generation since a considerable amount of quantization noise arises out-of-band.…”

Section: Transmittersmentioning

confidence: 99%

“…By adding the Tx modulated spur to the mixer output signal and using (6), (9), and (10), the total signal before the Analog-to-Digital Conversion (ADC) can be expressed as…”

Section: Baseband Modeling Of the Self-interferencementioning

confidence: 99%

Digitally-intensive transceivers for future mobile communications—emerging trends and challenges

Kanumalli

Buckel

Preissl

et al. 2018

Elektrotech. Inftech.

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This article presents an overview of the major trends and challenges involved with the design of multi-band, multi-standard digitallyintensive radio frequency transceivers for next generation mobile communications. In addition, we discuss in detail one aspect of the implementation challenges, namely the occurrence and cancellation of self-interference especially in carrier aggregation modes. For that, we present a novel digital cancellation technique to jointly compensate the self-interference caused by transmit (Tx) modulated spurs and Tx second order intermodulation distortion products (IMD2) in the receiver. This architecture exploits the underlying relation between both types of interference and offers a low-complexity solution to mitigate the Tx-IMD2 interference. Simulation results show, that the proposed technique significantly suppresses both types of interference and restores the signal-to-noise ratio of the wanted signal within 0.3 dB from its value in the absence of interference, thereby achieving 30 dB of cancellation.Keywords: RF; mobile communications; wireless communications; signal processing; interference cancellation; carrier aggregation Digital unterstützte Hochfrequenz-Transceiver für den Mobilfunk der Zukunft -Trends und Herausforderungen. Dieser Artikel gibt zunächst einen Überblick über aktuellen Trends und Herausforderungen bei der Entwicklung von Multi-Band, Multi-Standard HF-Transceivern für die nächste Mobilfunk-Generation, die einen hohen Anteil an digitaler Elektronik aufweisen. Im Anschluss wird im Detail auf ein spezielles Problem solcher Transceiver eingegangen, nämlich der Selbst-Interferenz, die durch den eigenen Sender verursacht wird und die vor allem im Carrier Aggregation-Modus auftritt. Die Problematik wird nicht nur detailliert erklärt, diese Arbeit präsentiert auch eine Methode zur Unterdrückung von Selbst-Interferenz mit den Mitteln der digitalen

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A Nonlinear Switched State-Space Model for Capacitive RF DACs

Cited by 15 publications

References 17 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

Digitally-intensive transceivers for future mobile communications—emerging trends and challenges

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