Enabling Millimeter Wave Circuit Techniques For High Data Rate Communication

This dissertation has been mainly focused on reconfigurable mm-wave integrated circuits for next generation wireless communication systems (namely, 5G). One of the major approaches to making 5G a reality is the use of high-frequency signals in the millimeter-wave (mm-wave) frequency band to facilitate access to more bandwidth. This can deliver faster and more reliable data to more users. This dissertation contributes to making wideband, bidirectional, and scalable RFICs for high data rate point-to-point communications over large distances in mm-wave bands, particularly the E-band (71-76 GHz, 81-86 GHz). The E-band is a licensed band in the US, with 10 GHz of bandwidth allocated to low-cost, high-capacity, and point-to-point communication. For backhaul base-stations or air-to-ground communication, a scalable and large-element phased array is desired to acquire the appropriate isotropic radiated power and signal to noise ratio. Additionally, bidirectional operation supporting transmit (TX) and receive (RX) in a single aperture is desirable to minimize the area and save power. This dissertation has focused on new architectures for scalable, bidirectional, and wideband phased arrays using IBM\textquoteright s fastest SiGe technology, 90 nm. In this dissertation, the first E-band scalable phased-array transceiver is proposed based on coupled oscillator architecture. Coupled oscillator phased arrays have the advantage of low power and low complexity, resulting in an architecture that easily scales to the number of elements as multiple die can be aggregated to form a larger array through local oscillator (LO) power distribution and intermediate frequency (IF) power combining. However, silicon processes introduce undesirable parasitics and manufacturing tolerances to the transistor and passive devices. When multiple oscillators are present in a single die, the oscillators couple through the substrate. The substrate coupling introduces additional parasitic coupling paths between oscillators; this causes pulling and, consequently, amplitude and phase variation between the oscillators. In addition, the parasitics from the injection node to the substrate deviate the ILO performance from its ideal behavior. Conventional analysis of the amplitude and phase noise typically ignores the effect of the silicon substrate parasitic effects. This dissertation investigated the nonlinear dynamics of an injection-locked oscillator (ILO), where the effective circuit parameters of ILO performance were observed. More specifically, new amplitude and phase equations are derived that took into account the transistor\textquoteright s device parasitics and silicon substrate\textquoteright s parasitic coupling effects, including the transistor injection node parasitic capacitance ($C_{P}$), substrate parasitic conductive ($R_{sub}$) and dielectric ($C_{j}$) features. The derived models are compared with both the simulation and measurement results. The proposed 2x2 transceiver phased array block diagram described in this dissertation employs 4 injection-locked oscillators (ILOs) operating at a lower frequency range (in this case, 1/4 of the desired LO frequency), followed by a frequency quadrupler, to form a beam in transmit and receive modes. The bidirectional front-end is designed to operate at E-band within 3-dB bandwidth. Since the ILO-based phase shifting is technically challenging at millimeter-wave bands due to the parasitics of the injection circuitry and the oscillator phase noise trade-offs, the high-frequency limitations of the ILO phase shifter is considered and wide locking range and a less parasitic sensitive solution for current injection using folded-cascode architecture is proposed. The proposed ILO-based phase array architecture result in low phase noise and low channel to channel isolation supporting 6 Gb/s data rate at 256 QAM modulation. The conventional architectures of the E-band transceiver require a wide tuning range, around 10 GHz, for the LO signal and wide-bandwidth IF blocks. The wide-bandwidth requirement of LO and IF frequency for mm-waves increases the power consumption and complexity of the system. This dissertation proposes a novel architecture, named the \textquotedblleft Image-selection\textquotedblright{} E-band phased array. This new architecture makes the upper-band (81-86 GHz) and the lower-band (71-76 GHz) of the E-band spectrum images of each other in comparison to the LO signal, which is located at the center frequency (78.5 GHz). Therefore, an image rejection architecture is desired to select the wanted band while rejecting the other. The significant advantage of this architecture is that it only requires an LO with the quadrature phases within a tuning range lower than 1 GHz . This will relax the system design trade-offs to the circuit impairments. For bidirectional operation purpose and preventing use of quadrature generation circuitry at direct intermediate frequency (IF) or radio frequency (RF) signal paths, sliding-IF weaver architecture mixers are employed with the phase inverter in the divider path to select the upper or lower band. This architecture leads in to a flat conversion gain over the bandwidth and low amplitude and phase imbalance. The achieved QAM modulation data rate from this technique is the state of art,\lyxdeleted{najmebi}{Mon May 29 19:43:48 2017}{ } 9Gb/s (64 QAM) with less than 5\% EVM and 12 Gb/s (16 QAM) with less than 10\% EVM.

The increasing demand for extremely high-data-rate communications has urged researchers to develop new communication systems. Currently, wireless transmission with more than one Giga-bits-per-second (Gbps) data rates is becoming essential due to increased connectivity between different portable and smart devices. To realize Gbps data rates, millimeter-wave (MMW) bands around 60 GHz is attractive due to the availability of large bandwidth of 9 GHz. Recent research work in the Gbps data rates around 60 GHz band has focused on short-range indoor applications, such as uncompressed video transfer, high-speed file transfer between electronic devices, and communication to and from kiosk. Many of these applications are limited to 10 m or less, because of the huge free space path loss and oxygen absorption for 60 GHz band MMW signal. This book introduces new knowledge and novel circuit techniques to design low-power MMW circuits and systems. It also focuses on unlocking the potential applications of the 60 GHz band for high-speed outdoor applications. The innovative design application significantly improves and enables high-data-rate low-cost communication links between two access points seamlessly. The 60 GHz transceiver system-on-chip provides an alternative solution to upgrade existing networks without introducing any building renovation or external network laying works.

The millimeter-wave frequency band (30–300 GHz) is considered a potential candidate to host very high data rate communications. First used for high capacity radio links and then for broadband indoor wireless networks, the interest in this frequency band has increased as it is proposed to accommodate future 5G mobile communication systems. The large bandwidth available will enable a number of new uses for 5G. In addition, due to the large propagation attenuation, this frequency band may provide some additional advantages regarding frequency reuse and communication security. However, a number of issues have to be addressed to make mm-wave communications viable. This book collects a number of contributions that present solutions to these challenges.

This book presents design methods and considerations for digitally-assisted wideband millimeter-wave transmitters. It addresses comprehensively both RF design and digital implementation simultaneously, in order to design energy- and cost-efficient high-performance transmitters for mm-wave high-speed communications. It covers the complete design flow, from link budget assessment to the transistor-level design of different RF front-end blocks, such as mixers and power amplifiers, presenting different alternatives and discussing the existing trade-offs. The authors also analyze the effect of the imperfections of these blocks in the overall performance, while describing techniques to correct and compensate for them digitally. Well-known techniques are revisited, and some new ones are described, giving examples of their applications and proving them in real integrated circuits.

Spectrum scarcity is a longstanding problem in mobile telecommunications networks. Specifically, accommodating the ever-growing data rate and communications demand in the extensively used spectrum between 800 MHz and 6 GHz is becoming more challenging. For this reason, in the last years, communications in the millimeterwave (mm-wave) frequency range (30-300 GHz) have attracted the interest of many researchers, who consider mm-wave communications a key enabler for upcoming generations of mobile communications, i.e., 5G and 6G. However, the signal propagation in the mm-wave frequency range is subject to more challenging conditions. High path loss and penetration loss may lead to short-range communications and frequent transmission interruptions when the signal path between the transmitter and the receiver is blocked. In this dissertation, we analyze and optimize techniques that enhance the robustness and reliability of mm-wave communications. In the first part, we focus on approaches that allow user equipment (UE) to establish and maintain connections with multiple access points (APs) or relays, i.e., multi-connectivity (MC) and relaying techniques, to increase link failure robustness. In such scenarios, an inefficient link scheduling, i.e., over or under-provisioning of connections, can lead to either high interference and energy consumption or unsatisfied user’s quality of service (QoS) requirements. In the first paper, we propose a novel link scheduling algorithm for network throughput maximization with constrained resources and quantify the potential gain of MC. As a complementary approach, in the second paper, we solve the problem of minimizing allocated resources while satisfying users’ QoS requirements for mm-wave MC scenarios. To deal with the channel uncertainty and abrupt blockages, we propose a learning-based solution, of which the results highlight the tradeoff between reliability and allocated resource. In the third paper, we perform throughput and delay analysis of a multi-user mm-wave wireless network assisted by a relay. We show the benefits of cooperative networking and the effects of directional communications on relay-aided mm-wave communications. These, as highlighted by the results, are characterized by a tradeoff between throughput and delay and are highly affected by the beam alignment duration and transmission strategy (directional or broadcast). The second part of this dissertation focuses on problems related to mm-wave communications in industrial scenarios, where robots and new industrial applications require high data rates, and stringent reliability and latency requirements. In the fourth paper, we consider a multi-AP mm-wave wireless network covering an industrial plant where multiple moving robots need to be connected. We show how the joint optimization of robots’ paths and the robot-AP associations can increase mm-wave robustness by decreasing the number of handovers and avoiding coverage holes. Finally, the fifth paper considers scenarios where robot-AP communications are assisted by an intelligent reflective surface (IRS). We show that the joint optimization of beamforming and trajectory of the robot can minimize the motion energy consumption while satisfying time and communication QoS constraints. Moreover, the proposed solution exploits a radio map to prevent collisions with obstacles and to increase mm-wave communication robustness by avoiding poorly covered areas.

In the quest to increase channel bandwidths in wireless communication systems, two important trends are to move towards wider continuous bands at mm-wave frequencies and to aggregate smaller bands at cellular frequencies. In this dissertation a few of the challenges and possible circuit and DSP solutions for efficient high data rate communication using these techniques are described. First, an issue relating to cellular uplink carrier aggregation is discussed and a DSP based solution developed. Second, the design of a broad band CMOS PA for mm-wave applications is presented. Third, the design of an mm-wave predistortion system and its use to predistort an array of mm-wave CMOS SOI PAs is described. In the near term, cellular carriers plan on employing carrier aggregation to increase data rates. This can lead to significant receiver desensitization for a number of LTE band combinations, because of the cross-modulation products created by the nonlinearity of RF front-end components. To mitigate this effect, an all-digital cancellation algorithm is proposed in this thesis that canceled the cross-modulation product and improved the signal-to-interference-plus-noise ratio (SINR) and error-vector-magnitude (EVM) of the desired received signal by up to 20 dB. In the second part of the dissertation, the possibility of using mm-wave CMOS PAs for wideband communication is described. The design of CMOS stacked-FET PAs with an emphasis on appropriate complex impedances between the transistors is presented. The stacking of multiple FETs enables the use of higher supply voltages, which in turn allows higher output power and a broader bandwidth output matching network. A 4-stack amplifier design that achieves a saturated output power greater than 21 dBm while achieving a maximum power-added-efficiency (PAE) greater than 20% from 38 GHz to 47 GHz is reported. Finally, the thesis describes predistortion of an array of stacked-FET PAs after spatial power combining. Predistortion improved the signal quality to a high level, which allowed the use of complex modulation schemes, which in turn allows high data rates in a spectrally efficient manner. After predistortion a 100-MHz wide, 1024-QAM signal was demodulated with an EVM of 1.3%, which corresponds to a data rate of 1 Gb/s.

High Frequency Communication and Sensing: Traveling-Wave Techniques introduces novel traveling wave circuit techniques to boost the performance of high-speed circuits in standard low-cost production technologies, like complementary metal oxide semiconductor (CMOS). A valuable resource for experienced analog/radio frequency (RF) circuit designers as well as undergraduate-level microelectronics researchers, this book: Explains the basics of high-speed signaling, such as transmission lines, distributed signaling, impedance matching, and other common practical RF background material Promotes a dual-loop coupled traveling wave oscillator topology, the trigger mode distributed wave oscillator, as a high-frequency multiphase signal source Introduces a force-based starter mechanism for dual-loop, even-symmetry, multiphase traveling wave oscillators, presenting a single-loop version as a force mode distributed wave antenna (FMDWA) Describes higher-frequency, passive inductive, and quarter-wave-length-based pumped distributed wave oscillators (PDWOs) Examines phased-array transceiver architectures and front-end circuits in detail, along with distributed oscillator topologies Devotes a chapter to THz sensing, illustrating a unique method of traveling wave frequency multiplication and power combining Discusses various data converter topologies, such as digital-to-analog converters (DACs), analog-to-digital converters (ADCs), and GHz-bandwidth sigma-delta modulators Covers critical circuits including phase rotators and interpolators, phase shifters, phase-locked loops (PLLs), delay-locked loops (DLLs), and more It is a significantly challenging task to generate and distribute high-speed clocks. Multiphase low-speed clocks with sharp transition are proposed to be a better option to accommodate the desired timing resolution. High Frequency Communication and Sensing: Traveling-Wave Techniques provides new horizons in the quest for greater speed and performance.

Wireless technology is redefining life and fueling socio-economic growth globally due to a dramatic increase in the use of mobile devices and growing number of data-hungry applications. However, the very success of wireless technology is leading to a severe spectrum crunch. Ongoing advances in the device and integrated circuit technology are enabling low-cost phased-array radios that can operate at millimeter-wave (mm-wave) bands as they provide very large bandwidth to meet data-rate demands. Future single-chip solution will require wideband circuits to support multiple mm-wave bands for a higher aggregate data-rate. In addition, low-power consumption and a compact circuit size are desired for battery-limited mobile radios as the power consumption and area of phased-array increases with the number of array elements.

The millimeter-wave frequency band (30-300 GHz) is considered a potential candidate to host very high data rate communications. First used for high capacity radio links and then for broadband indoor wireless networks, the interest in this frequency band has increased as it is proposed to accommodate future 5G mobile communication systems. The large bandwidth available will enable a number of new uses for 5G. In addition, due to the large propagation attenuation, this frequency band may provide some additional advantages regarding frequency reuse and communication security. However, a number of issues have to be addressed to make mm-wave communications viable. This book collects a number of contributions that present solutions to these challenges.

This book is based on the 18 tutorials presented during the 29th workshop on Advances in Analog Circuit Design. Expert designers present readers with information about a variety of topics at the frontier of analog circuit design, with specific contributions focusing on analog circuits for machine learning, current/voltage/temperature sensors, and high-speed communication via wireless, wireline, or optical links. This book serves as a valuable reference to the state-of-the-art, for anyone involved in analog circuit research and development.