Analog Circuits and Signal Processing. Series Editors Mohammed Ismail, Dublin, USA Mohamad Sawan, Montreal, Canada

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1 Analog Circuits and Signal Processing Series Editors Mohammed Ismail, Dublin, USA Mohamad Sawan, Montreal, Canada

2 More information about this series at

3 Marco Vigilante Patrick Reynaert 5G and E-Band Communication Circuits in Deep-Scaled CMOS 123

4 Marco Vigilante ESAT-MICAS KU Leuven Leuven Belgium Patrick Reynaert ESAT-MICAS KU Leuven Leuven Belgium ISSN X ISSN (electronic) Analog Circuits and Signal Processing ISBN ISBN (ebook) Library of Congress Control Number: Springer International Publishing AG, part of Springer Nature 2018 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Printed on acid-free paper This Springer imprint is published by the registered company Springer International Publishing AG part of Springer Nature The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

5 Preface We are at the dawn of a new era. New emerging applications will revolutionize the way we communicate, share ideas, work, travel, play, watch sports, and enjoy movies; in a single word, the way we live. For Internet of Things (IoT) applications, it is estimated that up to hundred devices will be connected and share information for each person, from wearable devices -(such as smartwatches) to disposable lab-on-a-chip (for smart health care). Those devices will generate an enormous amount of data, posing unprecedented challenges on each element of the network. For automotive applications, advanced driver assistance systems (ADAS) are expected to evolve in self-driving cars with automatic parking and predictive-collision-avoidance features. For mobile applications, virtual reality (VR) games and videos are expected in the near future. Fifth generation mobile networks (5G) is the wireless standard that will address these challenges. 100 higher data rate is needed at 100 higher network efficiency. For the network to provide high-quality services such as 3D 360 video and 360 surround solutions to enable virtual reality (VR) while being transparent to the user, better than 1 ms latency is needed. This is the first time that a wireless standard puts such stringent specifications to improve the user experience. To send so much data in such a limited time, an enormous amount of bandwidth is required. The spectrum in the low GHz range is already overcrowded; therefore, mm-wave wireless communication is going to happen in the near future. CMOS is the technology of choice for mass production digital circuits. It guarantees high yield and low costs, while the aggressive scaling of the minimum feature size allows to integrate low power mm-wave analog building blocks together with the baseband digital signal processing. CMOS is therefore a key technology for the success of 5G mm-wave front-ends and has attracted a growing attention in the last decade from both industries and research institutes. However, aggressive technology scaling does not provide only benefits. The low-level metal interconnections get thinner and closer to the substrate, seriously limiting the achievable f MAX of active devices and the maximum quality factor of on-chip passive devices. The supply voltage scales as well, making the classical analog design trade-offs tighter. Moreover, the requirements on large bandwidth of v

6 vi Preface operation should be met under process, voltage, and temperature (PVT) variations, and extra margin should be taken to allow substantial model inaccuracy due to the high frequency of operation. This work focuses on these challenges and proposes design techniques for several building blocks that currently limit the performance of mm-wave transceivers. The distinctive features of high-speed analog design in deep-scaled CMOS will be addressed, and a comparison with older technology node will be provided. Transformer-based low loss broadband filters that realize interstage matching, power division/combining, and impedance transformation will be discussed in great detail. Simple design equations that shed new insights on these pervasive kinds of filters will be provided. Second-order effects due to physical layout implementation will be addressed and simple solutions will be proposed. Tuning extension techniques for integrated mm-wave oscillators will be discussed. The design, layout, and measurements details of five state-of-the-art building blocks that leverage the proposed design techniques will be presented. (1) An E-Band quadrature voltage controlled oscillator tunable over two bands of almost 5 GHz each separated in frequency, while achieving state-of-the-art phase noise and power consumption is demonstrated. The integrated prototype realizes accurate quadrature phases and occupies only mm 2. (2) A wideband inductor-less frequency divide-by-4 that allows low power operation with wide margin over the whole E-Band (60 90 GHz) and beyond is reported for the first time. (3) A broadband low-noise amplifier for E-Band point-to-point communication links that achieves a figure of merit 10.5 db better than the state-of-the-art designs in the same band is shown. (4) The LNA is further integrated into a broadband sliding-if receiver that demonstrates 30.8 db conversion gain with 1 db in-band ripple over a 27.5 GHz BW 3dB while achieving a 7.3 db minimum NF with less than 2 db variation from 61.4 to 88.9 GHz. This wideband state-of-the-art performance enables robust and low power multi-gb/s wireless communication over short to medium distance over the complete E-Band with wide margin. (5) A GHz (65% BW) AM-PM compensated class-ab power amplifier tailored for 5G phased arrays is demonstrated. This integrated prototype shows outstanding AM-PM linearity allowing excellent EVM and ACPR while amplifying wideband modulated signals with high PAPR. All designs were implemented in a 28-nm CMOS technology without RF ultra-thick top metal option. Leuven, Belgium October 2017 Marco Vigilante Patrick Reynaert

7 Contents 1 Introduction Towards 5G and IoT mm-wave Spectrum, Challenges and Opportunities System Level Requirements for mm-wave Wireless Links Free Space Loss and Beamforming Impairments Model Link Budget Design Examples Outline of This Book References G m Stage and Passives in Deep-Scaled CMOS G m Stage: MOS as a Transconductor DC Model and Regions of Operation (I DS ) AC Model, Gain (g m ) and Speed (f t,f MAX ) Inversion Coefficient (IC) as a Design Parameter Effect of Scaling Effect of Scaling on Integrated Passives MOS Transistor as a Switch Capacitors Inductors Transformers Transmission Lines Conclusion References Gain-Bandwidth Enhancement Techniques for mm-wave Fully-Integrated Amplifiers RLC Tank RC Low-Pass Filter RLC Band-Pass Filter vii

8 viii Contents 3.2 Coupled Resonators Bode-Fano Limit Capacitively Coupled Resonators Inductively Coupled Resonators Magnetically Coupled Resonators Magnetically and Capacitively Coupled Resonators Coupled Resonators Comparison Transformer-Based Resonators On the Parasitic Interwinding Capacitance Effect of Unbalanced Capacitive Terminations Frequency Response Equalization On the Parasitic Magnetic Coupling in Multistage Amplifiers Extension to Impedance Transformation On the kq Product Transformer-Based Power Dividers Transformer-Based Power Combiners Conclusion References mm-wave LC VCOs LC VCOs Basics Negative Gm Model A General Result on Phase Noise More on Flicker Noise Upconversion and 2nd Order Effects Distributed Oscillators FOM and Tuning Extension Techniques Varactors Switched Capacitors Switched Inductors Switched TLs th Order Tanks and Other Techniques Design Example: A Dual-Band Transformer-Coupled QVCO in 28nm CMOS Proposed Transformer-Coupled Quadrature VCO Design Considerations at mm-wave and Circuit Implementation Measurement Results Appendix Conclusion References... 99

9 Contents ix 5 mm-wave Dividers Injection Locking: Operation Principle High Speed Dividers Injection Locked LC Dividers Current-Mode Logic (CML) Dividers Design Example: An Ultra-wideband Divide-by-4 in 28nm CMOS Design for Maximum Locking Range and Minimum Power Consumption in the E-Band Measurement Results Conclusion References mm-wave Broadband Downconverters Receiver Architectures Low-Noise Amplifiers Basics Most Adopted Circuits Cascode Limitations Neutralized CS Amplifier Broadband Input Match Downconversion Design Example 1: A Wideband LNA in 28nm CMOS LNA Architecture Measurement Results Design Example 2: A Wideband Downconverter Front-End in 28nm CMOS Receiver Architecture RF Mixer and Power Splitter If Mixer, Baseband TIA and I/Q Generation Measurement Results Conclusion References mm-wave Highly-Linear Broadband Power Amplifiers Power Amplifiers Basics Single Transistor Amplifier Under Large Signal Trade-Offs in PA Design: P o, PAE and Linearity Harmonic Terminations and Switching Amplifiers Class-AB Power Efficiency at Power Back-Off Sources of AM-PM Distortion Distortion Cancellation Techniques

10 x Contents 7.3 Design Example: A Highly Linear Wideband PA in 28nm CMOS Broadband Impedance Transformation Transformer-Based Output Combiner and Inter-stage Power Divider More on the kq Product Measurement Results Appendix I Appendix II Conclusion References Conclusion Summary Major Contributions Suggestions for Future Work References Index