Modeling and predistortion for digital transmitters based on delta-sigma and pulse-width modulation

Ding, Lei; Hezar, Rahmi; Erez, Shai

doi:10.1109/mwsym.2016.7540158

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…Hence, the output of the RF-DAC v DAC [k] is linear in the unknown parameter vector a j m using the model of the supply network distortion, as shown in (18). From (27), one can thus derive a linear estimator such as the linear (complex-valued) least-squares estimator to estimate the unknown coefficient vector [46], [47], i.e.,…”

Section: Parameter Estimationmentioning

confidence: 99%

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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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Section: Parameter Estimationmentioning

confidence: 99%

“…Nevertheless, also RF-DACs suffer from internal and external nonidealities, limiting their linearity. Hence, DPD concepts have also been proposed for RF-DAC-based transmitters [23]- [27]. These published DPD systems use conventional black-box approaches to model and hence mitigate the nonlinear effects.…”

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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show abstract

“…An exact baseband equivalent model for a quadrature modulated ADT was given in [9], but only for 2 level pulse encoding scheme (taking precisely ±1 values), and without an obvious extension to multi-level case. An analog baseband equivalent model was recently given in [10]. Effects of pulse encoder are completely ignored in the derivation of equivalent model, thus neglecting large amount of quantization noise in the PA input, which spectrally spreads into signal band once processed by the passband nonlinearity.…”

Section: Introductionmentioning

confidence: 99%

Novel baseband equivalent models of quadrature modulated all-digital transmitters

Tanovic

Teo

2017

2017 IEEE Radio and Wireless Symposium (RWS)

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In this paper an exact baseband equivalent model of a quadrature modulated all-digital transmitter is derived. No restrictions on the number of levels of a digital switched-mode power amplifier (SMPA) driving input, nor the pulse encoding scheme employed, are made. This implies a high level of generality of the proposed model. We show that all-digital transmitter (ADT) can be represented as a series connection of the pulse encoder, discrete-time Volterra series model of fixed degree and memory depth, and a linear timevarying system with special properties. This result suggests a new analytically motivated structure of a digital predistortion (DPD) of SMPA nonlinearities in ADT. Numerical simulations in MATLAB are used to verify proposed baseband equivalent model.Index Terms-Digital predistortion, all-digital transmitter, baseband equivalent model.

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Channelized active noise elimination (CANE) for suppressing quantization noise in bitstream modulated transmitter (BMT)

Zhu

Song

Wang

2021

J Wireless Com Network

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Bitstream modulated transmitters may offer improved power efficiency and linearity simultaneously in RF power amplifiers. Several modulation techniques including envelop delta-sigma modulation and envelope pulse width modulation have been applied. The out-of-band quantization noise associated with these modulations may be rejected by a high-quality factor output filter, yet the in-band quantization noise needs to be further suppressed to meet the requirement of the emission mask. The proposed channelized active noise elimination technique can offer additional quantization noise suppression through software control without involving a passive filter. The essential concept is based on combining the outputs of multiple channels of Pas that have digitally controlled delays to form a FIR filter in analogue domain. A two-channel and a four-channel GaN power amplifiers are built to demonstrate this noise suppression concept and power combiners based on T-junction with quarter wavelength transmission line are proposed to retain the high power efficiency of the transmitters.

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Modeling and predistortion for digital transmitters based on delta-sigma and pulse-width modulation

Cited by 4 publications

References 7 publications

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

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

Novel baseband equivalent models of quadrature modulated all-digital transmitters

Channelized active noise elimination (CANE) for suppressing quantization noise in bitstream modulated transmitter (BMT)

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