A W-Band On-Wafer Active Load-Pull System Based on Down-Conversion Techniques

A new W-band active load-pull system is presented. It is the first load-pull system to implement a 94 GHz load by means of an active loop exploiting frequency conversion techniques. The active loop configuration demonstrates a number of advantages that overcome the typical limitations of W-band passive tuners or conventional active open loop techniques in a cost effective way: load reflection coefficients Γ L as high as 0.95 in magnitude can be achieved at 94 GHz, thus providing a nearly full coverage of the Smith Chart. Possible applications of the setup include technology assessment, large-signal device model verification at sub-THz frequencies, and W-band MMIC design and characterization. The availability of direct and accurate load-pull measurements at W-band should prove an asset in the development of sub-THz integrated circuits. First measure- ments performed on high performance InP double heterojunction bipolar transistors (DHBTs) and GaN high electron mobility transistors (HEMTs) are presente

Millimeter-wave load-pull techniques

In this talk, the challenges in the realization of on-wafer large-signal measurement systems in W-band will be summarized and a recent implementation of a W-band on-wafer load-pull system will be presented. The availability of W-band large signal set-ups opens several possibilities, ranging from technology assessment and large-signal device modeling at sub-THz frequencies, to W-band MMIC design and characterization. Direct and accurate load-pull measurements at W-band are thus crucial in the development of sub-THz integrated circuits. The main issue at these frequencies is the realization of highly reflective loads at the on-wafer reference planes. In-situ tuners can solve this problem, but they need to be integrated with the device under test and this is not always possible. Passive mechanical tuners could be a solution, but the losses between tuner and probe tip need to be compensated in some way, otherwise the reachable reflection coefficients will present severe magnitude limitations. An active load clearly overcomes this limit and in addition, with an active load, measurement directional couplers can be placed in real-time configuration and achieve higher accuracy than purely passive systems. Active loads can be implemented in open- or closed-loop configuration. The realized system is the first load-pull system to implement a 94 GHz load by means of an active loop exploiting frequency conversion techniques. This has advantages in cost and load stability. The system is based on a HP8510 vector network analyzer. Its performances in terms of reachable load, load stability, speed and residual uncertainty will be shown and compared to a 40 GHz load-pull system based on a PNA-X. Finally, the first measurements performed on high performance InP double heterojunction bipolar transistors (DHBTs) and GaN high electron mobility transistors (HEMTs) will be presented

W/D-Bands single-chip systems in a 0.13μm SiGe BiCMOS technology-dicke radiometer, and frequency extension module for VNAs

Recent advances in silicon-based process technologies have enabled to build low-cost and fully-integrated single-chip millimeter-wave systems with a competitive, sometimes even better, performance with respect to III-V counterparts. As a result of these developments and the increasing demand for the applications in the millimeter-wave frequency range, there is a growing research interest in the field of the design and implementation of the millimeter-wave systems in the recent years. In this thesis, we present two single-chip D-band front-end receivers for passive imaging systems and a single-chip W-band frequency extension module for VNAs, which are implemented in IHP’s 0.13μm SiGe BiCMOS technology, SG13G2, featuring HBTs with ft/fmax of 300GHz/500GHz. First, the designs, implementations, and measurement results of the sub-blocks of the radiometers, which are SPDT switch, low-noise amplifier (LNA), and power detector, are presented. Then, the implementation and experimental test results of the total power and Dicke radiometers are demonstrated. The total power radiometer has a noise equivalent temperature difference (NETD) of 0.11K, assuming an external calibration technique. In addition, the dependence of the NETD of the total power radiometer upon the gain-fluctuation is demonstrated. The NETD of the total power radiometer is 1.3K assuming a gain-fluctuation of %0.1. The front-end receiver of the total power radiometer occupies an area of 1.3 mm2. The Dicke radiometer achieves an NETD of 0.13K, for a Dicke switching of 10 kHz, and its total chip area is about 1.7 mm2. The quiescent power consumptions of the total power and Dicke radiometers are 28.5 mW and 33.8 mW, respectively. The implemented radiometers show the lowest NETD in the literature and the Dicke switching concept is employed for the first time beyond 100 GHz. Second, we present the design methodologies, implementation methods, and results of the sub-blocks of the frequency extension module, such as down-conversion mixer, frequency quadrupler, buffer amplifier, Wilkinson power divider, and dual-directional coupler. Later, the implementation, characterization and experimental test results of the single-chip frequency extension module are demonstrated. The frequency extension module has a dynamic range of about 110 dB, for an IF resolution bandwidth of 10 Hz, with an output power which varies between -4.25 dBm and -0.3 dBm over the W-band. It has an input referred 1-dB compression point of about 1.9 dBm. The directivity of the frequency extension module is better than 10 dB along the entire W-band, and its maximum value is approximately 23 dB at around 75.5 GHz. Finally, the measured s-parameters of a W-band horn-antenna, which are performed by either the designed frequency extension module and a commercial one, are compared. This study is the first demonstration of a single-chip frequency extension module in a silicon-based semiconductor technology

Metriwave final report

The superconductor-insulator-superconductor (SIS) mixer is a device which is being used in the construction of very sensitive receivers in the millimeter and submillimeter wavelength regions. With its potential for conversion gain and quantum-limited performance, it is becoming a device of prime importance in radio astronomy as well as earth and planetary atmospheric research. Many of the parameters of the SIS mixer cannot be readily measured in the laboratory, however, since most commercially available test instruments use test signal powers large enough to saturate or destroy SIS junctions. Detailed here is the construction of a microwave network analyzer with extremely low test signal powers. The results of a development performed by Dynamics Technology, Inc., under a Phase 2 SBIR contract from NASA (NAS7-1025) are documented. The work resulted in a network analyzer to be delivered to workers at the Jet Propulsion Laboratory, which should be capable of SIS mixer characterization in support of their ongoing work in this area

Mesures load-pull multiharmoniques avec forme d'onde et application à la conception d'amplificateurs micro-ondes en classe F

Le réflectomètre six-ports -- Le système source-pull/load-pull automatique -- Calibration pour mesure de forme d'onde -- Système de mesure de forme d'onde -- Conception des amplificateurs de validation

Nanodevices for Microwave and Millimeter Wave Applications

The microwave and millimeter wave frequency range is nowadays widely exploited in a large variety of fields including (wireless) communications, security, radar, spectroscopy, but also astronomy and biomedical, to name a few. This Special Issue focuses on the interaction between the nanoscale dimensions and centimeter to millimeter wavelengths. This interaction has been proven to be efficient for the design and fabrication of devices showing enhanced performance. Novel contributions are welcome in the field of devices based on nanoscaled geometries and materials. Applications cover, but not are limited to, electronics, sensors, signal processing, imaging and metrology, all exploiting nanoscale/nanotechnology at microwave and millimeter waves. Contributions can take the form of short communications, regular or review papers

Measurement techniques for the characterization of radio frequency gallium nitride devices and power amplifiers

The rapid growth of mobile telecommunications has fueled the development of the fifth generation (5G) of standards, aiming to achieve high data rates and low latency. These capabilities make use of new regions of spectrum, wider bandwidths and spectrally efficient modulations. The deployment of 5G relies on the development of radio-frequency (RF) technology with increased performance. The broadband operation at high-power and high-frequency conditions is particularly challenging for power amplifiers (PA) in transmission stages, which seek to concurrently maximize linearity and energy efficiency. The properties of Gallium Nitride (GaN) allow the realization of active devices with favorable characteristics in these applications. However, GaN high-electron mobility transistors (HEMTs) suffer from spurious effects such as trapping due to physical defects introduced during the HEMT growth process. Traps dynamically capture and release mobile charges depending on the applied voltages and temperature, negatively affecting the RF PA performance. This work focuses on the development of novel measurement techniques and setups to investigate trapping behavior of GaN HEMTs and PAs. At low-frequency (LF), charge dynamics is analyzed using pulsed current transient characterizations, identifying relevant time constants in state-of-the-art GaN technologies for 5G. Instead, at high-frequency, tailored methods and setups are used in order to measure trapping effects during the operation of HEMTs and PAs in RF modulated conditions. These RF characterizations emulate application-like regimes, possibly involving the control of the device’s output load termination. Therefore, an innovative wideband active load pull (WALP) setup is developed, using the acquisition capabilities of standard vector-network-analyzers. Moreover, the implications of performing error-vector-magnitude characterizations under wideband load pull conditions are studied. Finally, an efficient implementation of a modified-Volterra model for RF PAs is presented, making use of a custom vector-fitting algorithm to simplify the nonlinear memory operators and enable their realization in simulation environments

Amplificadores de potência para radiofrequência insensíveis à impedância de carga

Solid state power amplifiers (SSPAs) evolved significantly over the last few decades, mainly, due to the use of new transistor technologies, such as gallium nitride (GaN) high-electron-mobility transistors (HEMTs), very advanced computer-aided design (CAD) software, and very effective digital pre-distortion (DPD) algorithms. This led to a considerable performance improvement, in terms of energy efficiency, output power, and linearity. To achieve this performance, power amplifier (PA) designers normally push the used transistors very close to their physical safe operating limits, and consider them to operate for a fixed output load. However, the designed PAs are used for many different industrial and/or telecommunication applications, and, in some cases, such as, for example, microwave cooking or massive multiple-input multiple-output (MIMO) fifth generation (5G) base stations (BSs), the output load of these amplifiers can change. Under this nonoptimal scenario, the used transistors will operate for non-nominal loads, and the PAs performance can be severely degraded. Moreover, in highly optimized designs, where the transistors are operated close to their safe limits, their reliability can be reduced or, in extreme cases, they can even be permanently damaged. Therefore, load insensitive PA architectures, and/or techniques that aim at reducing the load variation seen by the PA, are necessary to improve the performance under load varying scenarios. This thesis presents various strategies to improve load insensitiveness of PAs. The presented techniques are based on tunable matching networks (TMNs) and on the amplifiers’ drain supply voltage (VDS) variation. The developed TMNs successfully reduced the load variation seen by the PA, and its performance was greatly improved, for non-optimal loading, by also using the derived load dependent VDS variation. These different approaches were tested and validated on single-ended PAs and then, based on their advantages and disadvantages, the most promising technique – the supply voltage modulation – was selected for the design of a Doherty power amplifier (DPA), which is of paramount importance for telecommunication applications. Moreover, since in some applications the output load variation can be unpredictable, we also developed a complete quasi-load insensitive (QLI) PA system that includes an impedance tracking circuit and an automatic real-time compensation of the amplifier performance.Os amplificadores de potência de estado sólido (SSPAs) evoluíram significativamente nas últimas décadas, principalmente devido à utilização de novas tecnologias de transístores, como os transístores de alta mobilidade (HEMTs) de nitreto de gálio (GaN), de ferramentas muito avançadas de projeto assistido por computador (CAD) e de algoritmos de pré-distorção digital (DPD) muito evoluídos. Isto levou a uma melhoria de desempenho considerável, em termos de eficiência energética, potência de saída e linearidade. Normalmente, para obter estes níveis de desempenho, os engenheiros projetam os amplificadores permitindo que os transístores utilizados operem muito perto do seu limite físico de funcionamento seguro e considerando que vão operar para uma carga fixa. No entanto, os amplificadores projetados são utilizados em diversas aplicações industriais e/ou telecomunicações e, em alguns casos, como por exemplo fornos micro-ondas ou estações base 5G, a sua carga de saída pode variar devido a várias causas, que podem ser previsíveis ou imprevisíveis. Neste cenário não ideal, os transístores utilizados operam para cargas não ótimas e o desempenho dos amplificadores pode ser muito degradado. Além disso, em projetos muito otimizados, onde os transístores são operados perto do seu limite de funcionamento seguro, a sua durabilidade pode ser reduzida ou, em casos extremos, podem até ser permanentemente danificados. Portanto, para melhorar o desempenho dos amplificadores em cenários de carga variável, são necessárias novas arquiteturas e/ou técnicas que visam reduzir a variação da carga vista pelos transístores utilizados. Esta tese apresenta várias estratégias para melhorar a insensibilidade dos amplificadores em relação à variação de carga. As técnicas apresentadas são baseadas em malhas de adaptação dinâmicas (TMNs) e na variação da tensão de alimentação dos amplificadores. As malhas de adaptação desenvolvidas permitiram reduzir a variação de carga vista pelo amplificador e a variação da sua tensão de alimentação permitiu melhorar o desempenho para operação com cargas não ótimas. Estas abordagens foram testadas e validadas em amplificadores baseados num só transístor, e, posteriormente, com base nas suas vantagens e desvantagens, a técnica mais promissora – a modulação da tensão de alimentação – foi selecionada para o projeto de um amplificador Doherty, que é imprescindível para telecomunicações. Além disso, como em algumas aplicações a variação da carga de saída pode ser imprevisível, também desenvolvemos um sistema completo que inclui um circuito de medida de impedância e compensação do desempenho do amplificador em tempo real.Programa Doutoral em Engenharia Eletrotécnic