A review of technologies and design techniques of millimeter-wave power amplifiers

his article reviews the state-of-the-art millimeter-wave (mm-wave) power amplifiers (PAs), focusing on broadband design techniques. An overview of the main solid-state technologies is provided, including Si, gallium arsenide (GaAs), GaN, and other III-V materials, and both field-effect and bipolar transistors. The most popular broadband design techniques are introduced, before critically comparing through the most relevant design examples found in the scientific literature. Given the wide breadth of applications that are foreseen to exploit the mm-wave spectrum, this contribution will represent a valuable guide for designers who need a single reference before adventuring in the challenging task of the mm-wave PA design

IC-Antenna Co-Integration for Efficient and Scalable Millimeter-Wave Antenna Interfaces

Millimeter-wave (mm-wave) technology promises high speed, high system capacity and low latency interconnects with reduced cost. Applications like high data-rate wireless links, next generation automotive sensors and security body scanners highly depend on mm-wave technology innovations. As operating frequency moves to higher mm-wave bands, shrinking antenna dimensions enable co-integration of IC and antenna. Limited transistor output power at mm-wave requires multi-element arrays to satisfy communication and radar link budgets. This dissertation presents a wafer-scale compatible IC-antenna co-integration for efficient and scalable mm-wave antenna interfaces. The proposed IC-antenna co-integration approach is demonstrated through single antenna transmitters, a concurrent dual-polarization receiver front-end and polarization-duplex transmitter/receiver front-end. Chapter 2 discusses the challenge of mm-wave IC-antenna interfaces with prior art including antenna-in-package (AiP) and on-chip antennas. The 60 GHz efficient, scalable and wafer-scale compatible IC-antenna co-integration approach is presented demonstrating wide bandwidth and large efficiency which are comparable to system-level AiP techniques at a lower cost and fabrication complexity. Chapter 3 extends the proposed approach to a concurrent 60 GHz dual-polarization receiver front-end for short-range imaging/communication applications and polarization diversity based MIMO links. Active cancellation between orthogonal polarizations is adopted to achieve ∼ 30 dB cross-polarization leakage cancellation and concurrent dual-pol reception. Chapter 4 presents a 60 GHz simultaneous transmit and receive front-end to achieve efficient polarization-duplex operation based on dual-polarization IC-antenna co-integration. Transmitter leakage is suppressed at receiver input and output by intrinsic antenna isolation and a feed-forward passive canceller. Total average self-interference cancellation >40 dB is achieved for 1.07 GHz RF bandwidth at 60 GHz in the presence of a reflector

Reconfigurable Receiver Front-Ends for Advanced Telecommunication Technologies

The exponential growth of converging technologies, including augmented reality, autonomous vehicles, machine-to-machine and machine-to-human interactions, biomedical and environmental sensory systems, and artificial intelligence, is driving the need for robust infrastructural systems capable of handling vast data volumes between end users and service providers. This demand has prompted a significant evolution in wireless communication, with 5G and subsequent generations requiring exponentially improved spectral and energy efficiency compared to their predecessors. Achieving this entails intricate strategies such as advanced digital modulations, broader channel bandwidths, complex spectrum sharing, and carrier aggregation scenarios. A particularly challenging aspect arises in the form of non-contiguous aggregation of up to six carrier components across the frequency range 1 (FR1). This necessitates receiver front-ends to effectively reject out-of-band (OOB) interferences while maintaining high-performance in-band (IB) operation. Reconfigurability becomes pivotal in such dynamic environments, where frequency resource allocation, signal strength, and interference levels continuously change. Software-defined radios (SDRs) and cognitive radios (CRs) emerge as solutions, with direct RF-sampling receivers offering a suitable architecture in which the frequency translation is entirely performed in digital domain to avoid analog mixing issues. Moreover, direct RF- sampling receivers facilitate spectrum observation, which is crucial to identify free zones, and detect interferences. Acoustic and distributed filters offer impressive dynamic range and sharp roll off characteristics, but their bulkiness and lack of electronic adjustment capabilities limit their practicality. Active filters, on the other hand, present opportunities for integration in advanced CMOS technology, addressing size constraints and providing versatile programmability. However, concerns about power consumption, noise generation, and linearity in active filters require careful consideration.This thesis primarily focuses on the design and implementation of a low-voltage, low-power RFFE tailored for direct sampling receivers in 5G FR1 applications. The RFFE consists of a balun low-noise amplifier (LNA), a Q-enhanced filter, and a programmable gain amplifier (PGA). The balun-LNA employs noise cancellation, current reuse, and gm boosting for wideband gain and input impedance matching. Leveraging FD-SOI technology allows for programmable gain and linearity via body biasing. The LNA's operational state ranges between high-performance and high-tolerance modes, which are apt for sensitivityand blocking tests, respectively. The Q-enhanced filter adopts noise-cancelling, current-reuse, and programmable Gm-cells to realize a fourth-order response using two resonators. The fourth-order filter response is achieved by subtracting the individual response of these resonators. Compared to cascaded and magnetically coupled fourth-order filters, this technique maintains the large dynamic range of second-order resonators. Fabricated in 22-nm FD-SOI technology, the RFFE achieves 1%-40% fractional bandwidth (FBW) adjustability from 1.7 GHz to 6.4 GHz, 4.6 dB noise figure (NF) and an OOB third-order intermodulation intercept point (IIP3) of 22 dBm. Furthermore, concerning the implementation uncertainties and potential variations of temperature and supply voltage, design margins have been considered and a hybrid calibration scheme is introduced. A combination of on-chip and off-chip calibration based on noise response is employed to effectively adjust the quality factors, Gm-cells, and resonance frequencies, ensuring desired bandpass response. To optimize and accelerate the calibration process, a reinforcement learning (RL) agent is used.Anticipating future trends, the concept of the Q-enhanced filter extends to a multiple-mode filter for 6G upper mid-band applications. Covering the frequency range from 8 to 20 GHz, this RFFE can be configured as a fourth-order dual-band filter, two bandpass filters (BPFs) with an OOB notch, or a BPF with an IB notch. In cognitive radios, the filter’s transmission zeros can be positioned with respect to the carrier frequencies of interfering signals to yield over 50 dB blocker rejection

Design and Characterization of Circuits for Next-Generation Wireless Communications Systems

Demand for wireless data transfer has been increasing rapidly with the rise of smart devices and mobile video streaming. With dozens of wireless applications currently in use and only a finite bandwidth to work with, engineers are challenged to both expand the upward frequency limit of high-performance, high-efficiency wireless systems and to increase the spectral efficiency of the frequency bands already in use. The development of deep sub-um silicon-on-insulator transistor technology and powerful computer-aided circuit designing tools have allowed us to create more affordable silicon-based phased array ICs at frequencies previously achievable by only military applications. The 5th generation of mobile systems (5G) is now expected to use this type of IC to offer increased wireless data capacity in densely-populated areas using mm-wave frequencies. Demand for wireless data is only expected to continue rising, particularly as new IoT applications such as autonomous vehicles become commercially viable.The work presented in this dissertation addresses both the need for expanding the usable frequency spectrum and the need to increase spectral efficiency in available bands. It includes a design for an analog beamforming matrix for a spatially multiplexed phased array receiver in silicon SOI technology, low-power high-linearity w-band amplifiers in InP HBT technology, and ultra-wideband mm-wave power amplifiers in InP HBT technology. Spatially multiplexed phased array transceivers have the potential to greatly increase the spectral efficiency of mm-wave frequency bands by re-using frequency spectrum for many data channels. This type of system can be used to create short-range high-capacity line-of-sight wireless backhaul for crowded city squares or event venues. Mm-wave power amplifiers and high-linearity amplifiers in new 130 nm InP HBT technology represent an IC performance boost which pushes the frequency limits of feasible power-efficient wireless systems. The measured power amplifier ICs produce output power of larger than 16.5 dBm at the 3-dB gain compression condition from 50 GHz to 100 GHz, and a small signal gain of 15 dB over a 90 GHz 3-dB bandwidth. The peak power-added efficiency (PAE) is larger than 8% over that same frequency range. At 90 GHz, the ICs produce 22 dBm of saturated output power and 14.7% PAE. The measured high-linearity amplifier ICs demonstrate an output-referred 3rd order intercept (OIP3) of 22 dBm, a gain of 6.4 dB, and a noise figure below 7 dB at 100 GHz. New designs for an analog MIMO beamforming matrix IC, a 100-165 GHz power amplifier, and an improved w-band high-linearity amplifier are also outlined in this dissertation

Millimeterwellen On-Chip Antennensysteme für die Integration in SoC Applikationen

In dieser Arbeit werden Antennensysteme für Radar- und Kommunikationssysteme präsentiert. Zusätzlich wird ein QFN Gehäusekonzept erarbeitet. Bei den Antennensystemen für Kommunikationsanwendungen liegt der Fokus auf der Maximierung der abgestrahlten Leistung, um die Reichweite zu erhöhen. Es wird ein neuartiges Konzept zur Leistungskombination von parallelisierten Verstärkern aufgezeigt, bei dem die Signale der einzelnen Verstärker im Antennenelement kombiniert werden

Leistungsverstärker für den Einsatz in energiesparsamer Informations- und Kommunikationstechnik

Thematisch eingebettet in das Forschungsgebiet der energiesparsamen Informations- und Kommunikationstechnik (IKT), beschäftigt sich diese Dissertation mit dem Entwurf und der Analyse von Leistungsverstärkern (LV) für drahtlose Übertragungssysteme. Die Arbeit konzentriert sich einerseits auf den asymmetrischen Doherty-Leistungsverstärker (DPA), welcher in einem Ausgangsleistungs-Backoff (OBO) von mehr als 6 dB einen zusätzlichen Ef fizienzhochpunkt aufweist. Andererseits wird die Topologie des geschalteten inversen Klasse-E Verstärkers beleuchtet, der sich durch einen theoretischen Wirkungsgrad von 100 % auszeichnet und daher für den Einsatz in energiesparsamer IKT von besonderem Interesse ist. Das Breitbandverhalten des DPA wird zur Optimierung der Leistungseffizienz (PAE) theoretisch analysiert. Hierbei wird der Einfluss der charakteristischen Impedanz des Impedanzinverters (IT) im Main-Pfad untersucht. Daran anknüpfend werden drei asymmetrische Sub-6 GHz DPA mit unterschiedlichen IT entworfen. Labormessung ergeben eine maximale PAE zwischen 52 % und 63 % bei einer Ausgangsleistung von 41 dBm bis 42 dBm, was für einen derartigen LV mit einer Mittenfrequenz oberhalb von 3 GHz den höchsten Wert im Vergleich zum Stand der Technik darstellt. Neben diesem diskreten Aufbau werden zwei weitere integrierte asymmetrische DPA-Designs in Galliumnitrid (GaN) bzw. Siliziumgermanium (SiGe) vorgestellt. Für den GaN-DPA mit Chebyshev-Anpassnetzwerk wird in der Messung eine abweichende Phasenlage zwischen Peak- und Main-Pfad detektiert, die nachträglich durch Bonddrahtmodifikation auf dem Chip verbessert wird. Der Schaltkreis erreicht eine hohe PAE im OBO von 34 % bis 54 %. Der dritte Entwurf untersucht einen zweistufigen asymmetrischen DPA in SiGe, der auf einer Analyse des WLAN-Standards bei 60 GHz basiert. Diese Analyse ergibt ein Verhältnis von maximaler zu mittlerer Ausgangsleistung (PAPR) von 8 dB. Der LV erreicht im Frequenzbereich von 59 GHz bis 67 GHz den vergleichsweise höchsten Leistungsgewinn von 22 dB. Die inverse Klasse-E Topologie wird als Ausgangsstufe in einem polaren Vektormodulator mit niedriger Versorgungsspannung verwendet. Eine theoretische Analyse der Topologie zeigt, dass die für einen effizienten Betrieb erforderlichen Induktivitäten geringer sind als beim klassischen Klasse-E Verstärker. Der daraus resultierende geringere Bedarf an Chipfläche macht diese Topologie besonders für stark skalierte CMOS-Prozesse interessant. Es werden zwei integrierte Schaltkreise (IC) in 45 nm bzw. 22 nm CMOS entworfen. Das Prinzip des Vektormodulators wird mit dem in 45 nm gefertigten IC getestet. Zur Steigerung der Ausgangsleistung auf bis zu 19,3 dBm wird die Topologie in eine neuartige inverse Klasse-E Gegentaktstufe überführt. Die kompakte Schaltung zeichnet sich durch eine hohe relative Bandbreite von 70,5 % aus. Neben den rein schaltungstechnischen Inhalten der Arbeit wird in einer kollaborativen Studie das Reduktionspotential von Treibhausgasemissionen durch IKT untersucht. Ziel ist der interdisziplinäre Brückenschlag zwischen Umwelt- und Ingenieurwissenschaften, um die ganzheitliche Sichtweise auf das Thema energieeffizienter IKT zu erweitern. Am Beispiel deutscher Konferenzreisen für das Jahr 2030 wird anhand einer Szenarioanalyse gezeigt, dass die deutschen CO2-Emissionen durch den Einsatz neuartiger 2D/3D-Videokonferenzsysteme jährlich um bis zu 20, 51 MtCO2e gesenkt werden könnten. Dies entspräche rund 2,7 % der gesamtdeutschen Emissionen. In diesem Teil der Arbeit werden mögliche Chancen des IKT-Beitrags zur Erreichung der Klimaziele deutlich. Unklar bleibt allerdings, ob es zu Rebound-Effekten kommt und wie Ressourcenbedarf und Recycling der Technologie in Zukunft nachhaltig gestaltet werden können

AlGaN/GaN-HEMT power amplifiers with optimized power-added efficiency for X-band applications

This work has arisen out of the strong demand for a superior power-added efficiency (PAE) of AlGaN/GaN high electron mobility transistor (HEMT) high-power amplifiers (HPAs) that are part of any advanced wireless multifunctional RF-system with limited prime energy. Different concepts and approaches on device and design level for PAE improvements are analyzed, e.g. structural and layout changes of the GaN transistor and advanced circuit design techniques for PAE improvements of GaN HEMT HPAs