Wideband CMOS Data Converters for Linear and Efficient mmWave Transmitters
Doctoral thesis, 2022
With continuously increasing demands for wireless connectivity, higher carrier frequencies and wider bandwidths are explored. To overcome a limited transmit power at these higher carrier frequencies, multiple input multiple output (MIMO) systems, with a large number of transmitters and antennas, are used to direct the transmitted power towards the user. With a large transmitter count, each individual transmitter needs to be small and allow for tight integration with digital circuits. In addition, modern communication standards require linear transmitters, making linearity an important factor in the transmitter design.
In this thesis, radio frequency digital-to-analog converter (RF-DAC)-based transmitters are explored. They shift the transition from digital to analog closer to the antennas, performing both digital-to-analog conversion and up-conversion in a single block. To reduce the need for computationally costly digital predistortion (DPD), a linear and wellbehaved RF-DAC transfer characteristic is desirable. The combination of non-overlapping local oscillator (LO) signals and an expanding segmented non-linear RF-DAC scaling is evaluated as a way to linearize the transmitter. This linearization concept has been studied both for the linearization of the RF-DAC itself and for the joint linearization of the cascaded RF-DAC-based modulator and power amplifier (PA) combination. To adapt the linearization, observation receivers are needed. In these, high-speed analog-to-digital converters (ADCs) have a central role. A high-speed ADC has been designed and evaluated to understand how concepts used to increase the sample rate affect the dynamic performance.
In this thesis, radio frequency digital-to-analog converter (RF-DAC)-based transmitters are explored. They shift the transition from digital to analog closer to the antennas, performing both digital-to-analog conversion and up-conversion in a single block. To reduce the need for computationally costly digital predistortion (DPD), a linear and wellbehaved RF-DAC transfer characteristic is desirable. The combination of non-overlapping local oscillator (LO) signals and an expanding segmented non-linear RF-DAC scaling is evaluated as a way to linearize the transmitter. This linearization concept has been studied both for the linearization of the RF-DAC itself and for the joint linearization of the cascaded RF-DAC-based modulator and power amplifier (PA) combination. To adapt the linearization, observation receivers are needed. In these, high-speed analog-to-digital converters (ADCs) have a central role. A high-speed ADC has been designed and evaluated to understand how concepts used to increase the sample rate affect the dynamic performance.
CMOS
Efficient
MIMO
Predistortion
mmWave
RF-DAC
Wideband
SAR ADC
Linear
Linearization
EA, EDIT-huset, Hörsalsvägen 11
Opponent: Jeffrey Walling, Virginia Tech, Virginia, US
Author
Victor Åberg
Embedded Electronics Systems and Computer Graphics
A 2x6b 8GS/s 17-24GHz I/Q RF-DAC based Transmitter in 22nm FDSOI CMOS
IEEE Microwave and Wireless Components Letters,; Vol. 31(2021)p. 929-932
Journal article
An 11 GS/s 2×10 b 20–26 GHz Modulator using Segmented Non-Linear RF-DACs and Non-Overlapping LO signals
Digest of Papers - IEEE Radio Frequency Integrated Circuits Symposium,; (2022)p. 143-146
Paper in proceeding
RF PA Predistortion using Non-Linear RF-DACs
2022 IEEE Nordic Circuits and Systems Conference, NORCAS 2022 - Proceedings,; (2022)
Paper in proceeding
Design Considerations and Evaluation of a High-Speed SAR ADC
2018 IEEE Nordic Circuits and Systems Conference, NORCAS 2018: NORCHIP and International Symposium of System-on-Chip, SoC 2018 - Proceedings,; (2018)
Paper in proceeding
Capacity for Future Communication Needs
Mobile communication has a central role in providing the connectivity expected in the connected modern society. With every new generation, the capacity has increased and so has also the capacity demands presented by the users. It is predicted that in five years, the global mobile traffic will be more than four times larger than today. To fulfill these future demands, the frequency resources traditionally used for mobile communication are not sufficient. With the introduction of the latest mobile communication technology (5G), mmWave frequency bands with vast amounts of available bandwidth are introduced to provide the capacity so desperately needed.
Data converters play a central role in wideband transmitters, bridging the gap between the digital domain, where information is processed, and the analog domain, where the information is transported. However, the challenge is to make these data converters both wideband and power efficient while the strict signal quality requirements on mobile communication systems are met.
In this thesis, I evaluate wideband data converters, including both analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), for mmWave transmitters. I also evaluate a concept for improving the transmitter linearity, using no additional hardware other than the DAC scaling, for both power efficient and area efficient linearization of wideband signals. All this is to fulfill the capacity demands of tomorrow in a sustainable way.
Mobile communication has a central role in providing the connectivity expected in the connected modern society. With every new generation, the capacity has increased and so has also the capacity demands presented by the users. It is predicted that in five years, the global mobile traffic will be more than four times larger than today. To fulfill these future demands, the frequency resources traditionally used for mobile communication are not sufficient. With the introduction of the latest mobile communication technology (5G), mmWave frequency bands with vast amounts of available bandwidth are introduced to provide the capacity so desperately needed.
Data converters play a central role in wideband transmitters, bridging the gap between the digital domain, where information is processed, and the analog domain, where the information is transported. However, the challenge is to make these data converters both wideband and power efficient while the strict signal quality requirements on mobile communication systems are met.
In this thesis, I evaluate wideband data converters, including both analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), for mmWave transmitters. I also evaluate a concept for improving the transmitter linearity, using no additional hardware other than the DAC scaling, for both power efficient and area efficient linearization of wideband signals. All this is to fulfill the capacity demands of tomorrow in a sustainable way.
Areas of Advance
Information and Communication Technology
Infrastructure
Kollberg Laboratory
Subject Categories
Telecommunications
Communication Systems
Embedded Systems
Other Electrical Engineering, Electronic Engineering, Information Engineering
ISBN
978-91-7905-658-2
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5124
Publisher
Chalmers
EA, EDIT-huset, Hörsalsvägen 11
Opponent: Jeffrey Walling, Virginia Tech, Virginia, US