Establishing a New Form of Primary Impedance Standard at Millimeter-Wave Frequencies

This paper investigates the possibility of using layers of graphene to form primary impedance standards for millimeter-wave rectangular metallic waveguide. It is shown that standards with values of Y?, 2Y? and 3Y? can be produced by a monolayer, bilayer, or trilayer of graphene, respectively, where Y? is the characteristic admittance of the waveguide. These standards could then be used in the calibration of vector network analyzers

Design, Fault Modeling and Testing Of a Fully Integrated Low Noise Amplifier (LNA) in 45 nm CMOS Technology for Inter and Intra-Chip Wireless Interconnects

Research in recent years has demonstrated that intra and inter-chip wireless interconnects are capable of establishing energy-efficient data communications within as well as between multiple chips. This thesis introduces a circuit level design of a source degenerated two stage common source low noise amplifier suitable for such wireless interconnects in 45-nm CMOS process. The design consists of a simple two-stage common source structure based Low Noise Amplifier (LNA) to boost the degraded received signal. Operating at 60GHz, the proposed low noise amplifier consumes only 4.88 mW active power from a 1V supply while providing 17.2 dB of maximum gain at 60 GHz operating frequency at very low noise figure of 2.8 dB, which translates to a figure of merit of 16.1 GHz and IIP3 as -14.38 dBm

Metrology State-of-the-Art and Challenges in Broadband Phase-Sensitive Terahertz Measurements

The two main modalities for making broadband phase-sensitive measurements at terahertz (THz) frequencies are vector network analyzers (VNA) and time-domain spectrometers (TDS). These measuring instruments have separate and fundamentally different operating principles and methodologies, and they serve very different application spaces. The different architectures give rise to different measurement challenges and metrological solutions. This article reviews these two measurement techniques and discusses the different issues involved in making measurements using these systems. Calibration, verification, and measurement traceability issues are reviewed, along with other major challenges facing these instrument architectures in the years to come. The differences in, and similarities between, the two measurement methods are discussed and analyzed. Finally, the operating principles of electro-optic sampling (EOS) are briefly discussed. This technique has some similarities to TDS and shares application space with the VNA

A RISC-V SOC for Terahertz IoT Devices: Implementation and design challenges

Terahertz (THz) communication is considered a viable approach to augmenting the communication capacity of prospective Internet-of-Things (IoT) resulting in enhanced spectral efficiency. This study first provides an outline of the design challenges encountered in developing THz transceivers. This paper introduces advanced approaches and a unique methodology known as Modified Pulse-width Modulation (MPWM) to address the issues in the THz domain. In this situation involving a transceiver that handles complex modulation schemes, the presence of a mixed signal through a high-resolution digital-to-analog converter (DAC) in the transmitter greatly contributes to the limitation in maintaining linearity at high frequencies. The utilization of Pulse-width Modulation-based Digital-to-Analog Converters (PWM-DACs) has garnered significant attention among scholars due to its efficiency and affordability. However, the converters' performance is restricted by insufficient conversion speed and precision, especially in the context of high-resolution, high-order modulation schemes for THz wireless communications. The MPWM framework offers a multitude of adjustable options, rendering the final MPWM-DAC highly adaptable for a diverse array of application scenarios. Comparative performance assessments indicate that MPWM-DACs have enhanced conversion speed compared to standard PWM-DACs, and they also provide greater accuracy in comparison to Pulse-count Modulation DACs (PCM-DACs). The study presents a comprehensive examination of the core principles, spectrum characteristics, and evaluation metrics, as well as the development and experimental validation of the MPWM method. Furthermore, we present a RISC-V System-on-Chip (SoC) that incorporates an MPWM-DAC, offering a highly favorable resolution for THz IoT communications.Comment: 18 pages, 17 figures, journa

Millimeter wave experiment for ATS-F

A detailed description of spaceborne equipment is provided. The equipment consists of two transmitters radiating signals at 20 and 30 GHz from either U.S. coverage horn antennas or a narrow beam parabolic antenna. Three modes of operation are provided: a continuous wave mode, a multitone mode in which nine spectral lines having 180 MHz separation and spaced symmetrically about each carrier, and a communications mode in which communications signals from the main spacecraft transponder are modulated on the two carriers. Detailed performance attained in the flight/prototype model of the equipment is presented both under laboratory conditions and under environmental extremes. Provisions made for ensuring reliability in space operation are described. Also described the bench test equipment developed for use with the experiment, and a summary of the new technology is included

Submillimeter sources for radiometry using high power Indium Phosphide Gunn diode oscillators

A study aimed at developing high frequency millimeter wave and submillimeter wave local oscillator sources in the 60-600 GHz range was conducted. Sources involved both fundamental and harmonic-extraction type Indium Phosphide Gunn diode oscillators as well as varactor multipliers. In particular, a high power balanced-doubler using varactor diodes was developed for 166 GHz. It is capable of handling 100 mW input power, and typically produced 25 mW output power. A high frequency tripler operating at 500 GHz output frequency was also developed and cascaded with the balanced-doubler. A dual-diode InP Gunn diode combiner was used to pump this cascaded multiplier to produce on the order of 0.5 mW at 500 GHz. In addition, considerable development and characterization work on InP Gunn diode oscillators was carried out. Design data and operating characteristics were documented for a very wide range of oscillators. The reliability of InP devices was examined, and packaging techniques to enhance the performance were analyzed. A theoretical study of a new class of high power multipliers was conducted for future applications. The sources developed here find many commercial applications for radio astronomy and remote sensing

Techniques, Circuits and Devices for Noncontact Sensing through Wireless Coupling

Le tecnologie per la misurazione di grandezze fisiche senza contatto sono diventate sempre più centrali in vari settori, che vanno dal monitoraggio industriale alle applicazioni sanitarie. In questo contesto, la tesi si concentra sullo sviluppo e l'implementazione di tecniche innovative, circuiti elettronici e dispositivi per la rilevazione senza contatto. L’analisi presentata all'interno di questa tesi considera lo scenario del rilevamento senza contatto a distanza nel campo elettromagnetico lontano (far-field) e al rilevamento senza contatto di prossimità, sfruttando le interazioni elettromagnetiche in campo vicino (near field). Nell’ambito del rilevamento senza contatto a distanza, la tesi indaga l'uso delle onde elettromagnetiche per il monitoraggio non invasivo del livello di solidi granulari all’interno di silos. Questo sistema, sviluppato impiegando un sensore radar commerciale a onda continua modulata in frequenza, dimostra il potenziale di questa tecnologia nel monitoraggio non invasivo e senza contatto in contesti agricoli e industriali. Considerando invece lo scenario del rilevamento senza contatto di prossimità, la tesi fornisce un'analisi dell'interrogazione senza contatto di sensori passivi e ne presenta diversi approcci e applicazioni. Vengono affrontate le problematiche delle misurazioni senza contatto, proponendo alcune soluzioni per migliorarne l'affidabilità e l'accuratezza, permettendo in particolare di renderle indipendenti dalla distanza di interrogazione. In particolare, la tesi presenta un sistema per la misurazione senza contatto della frequenza di risonanza di risonatori MEMS piezoelettrici. La tecnica proposta sfrutta l'accoppiamento magnetico tra un’unità di interrogazione ed un’unità sensore ed è applicata in modo innovativo per la rilevazione della temperatura, sfruttando le proprietà dei risonatori a disco in nitruro di alluminio (AlN) su silicio sottile piezoelettrico (TPoS) ed una tecnica di interrogazione senza contatto a tempo commutato. Inoltre, la tesi presenta un’etichetta flessibile per la misurazione della temperatura corporea, che combina il rilevamento a contatto della temperatura con una lettura senza contatto dell’unità sensore sfruttandone l'accoppiamento magnetico con un unità di interrogazione. L’etichetta flessibile, che costituisce l'unità sensore, è composta da una bobina induttiva che consente l'accoppiamento magnetico, un condensatore ceramico utilizzato come elemento sensibile alla temperatura, sfruttandone il coefficiente di temperatura della capacità, ed un induttore aggiuntivo utilizzato per rendere la frequenza di risonanza del circuito risonante RLC indipendente dalla flessione dell’etichetta. In modo analogo, le tecniche di interrogazione proposte sono state applicate ad un nuovo metodo per l'interrogazione senza contatto di un sensore induttivo, utilizzato per rilevare target conduttivi. Il sistema proposto presenta una bobina avvolta collegata con un condensatore per formare un circuito LC risonante, la cui frequenza di risonanza cambia quando un target conduttivo viene introdotto nel campo magnetico generato dalla bobina stessa. Attraverso una bobina di interrogazione esterna, accoppiata elettromagneticamente al sensore induttivo, è possibile interrogare senza contatto il sensore induttivo, permettendo quindi la rilevazione a distanza di target conduttivi. Infine, lo studio esposto in questa tesi introduce una tecnica avanzata per l'interrogazione senza contatto di sensori resistivi passivi, sfruttando risonatori a cristallo di quarzo come dispositivo risonante e basandosi sulla stima del fattore di qualità del circuito che costituisce l’unità sensore. Il metodo proposto supera i limiti delle tecniche basate su misure di ampiezza, legati in particolare all'influenza della distanza di interrogazioneNoncontact sensing technologies have become increasingly central in a variety of fields, ranging from industrial monitoring to healthcare applications. In this context, the thesis focuses on the development and implementation of innovative techniques, electronic circuits, and devices for contactless sensing via wireless coupling, responding to the growing interest in noncontact measurement methods. The themes treated in this thesis regard both the scenario of distant noncontact sensing in the electromagnetic far field, and proximate wireless sensing, leveraging on near-field electromagnetic interactions. Each domain is distinctly characterized by its specific technologies, applications, and methodologies, reflecting their operational ranges and fundamental principles. In the domain of distant wireless sensing, the thesis investigates the use of electromagnetic waves for unobtrusive level monitoring of granular solids in silos. This system, developed employing a commercial frequency-modulated continuous-wave radar sensor, demonstrates the potential of this technology in unobtrusive monitoring in agricultural and industrial environments. Considering the proximate wireless sensing domain, the thesis provides an analysis of noncontact interrogation of passive sensors and it presents different approaches and applications. It addresses the challenges and offers solutions for enhancing the reliability and accuracy of contactless measurements, which can be advantageously independent of the interrogation distance. This can path the way to the development of low-cost, disposable and sustainable devices for healthcare and industrial applications. In particular, the thesis presents a system for the noncontact measurement of the resonant frequency of piezoelectric MEMS resonators. The technique exploits magnetic coupling between interrogation and sensor units, and it is innovatively applied for temperature sensing exploiting a thin-film piezoelectric on silicon (TPoS) aluminium nitride (AlN) disk resonators and a contactless interrogation time-gated technique. Furthermore, the thesis presents a flexible patch for body temperature measurement, combining contact sensing with contactless readout, and exploiting magnetic coupling between interrogation and sensor units. The flexible patch, forming the sensor unit, is composed of an inductive coil for magnetic coupling, a ceramic capacitor used as the temperature sensing element exploiting its temperature coefficient of capacitance and an additional inductor to make the resonant frequency of the resulting resonant RLC circuit independent from the bending of the patch. Similarly, interrogation techniques have been applied to a novel method for contactless interrogation of an inductive sensor used for detecting conductive targets. The system features a solenoidal coil connected with a capacitor to form a resonating LC circuit, whose resonant frequency changes when a conductive target is introduced in the generated magnetic field. An external interrogation coil electromagnetically coupled to the inductive sensor enables the wireless measurement for conductive target detection. Lastly, the study introduces an advanced technique for the contactless interrogation of passive resistive sensors. The novel approach exploits the resonant frequency stability and the high quality factor of a quartz crystal resonator, used as a resonant element, with a series-connected resistor acting as the sensing element. This method overcomes the limitations of amplitude measurements techniques typically affected by the interrogation distance

Optical and Quasi-Optical Design and Analysis of Astronomical Instrumentation including a Prototype SAFARI Pixel

The work of this thesis focuses primarily on the quasi-optical analysis of optical systems in the Terahertz region of the spectrum. This included the development of novel simulation techniques based on the principles of mode matching and gaussian beam mode analysis, which are uniquely suited to the simulation of electrically large optical systems at millimeter wavelengths. Additionally, several commercial software packages were used and experimental measurements conducted for the purpose of both validating the newly developed simulation techniques, as well as simulating / measuring specific elements beyond the scope of the in-house software. The main drivers behind this work were a Technology Research Programme of the European Space Agency, the optical payload design of the future proposed Space Infrared-Telescope for Cosmology and Astrophysics mission and work on the Atacama Large Millimeter Array. Once the simulation tools were developed and proven an analysis of these optical systems was conducted. In the case of the Atacama Large Millimeter Array this involved the analysis of the proposed system, whilst for the other projects of the European Space Agency, although an initial optical system was proposed, much work was also required in maturing the design as well as conducting a standard analysis. This was carried out in conjunction with the other groups of the Technology Research Programme, which included the Terahertz optics group of NUI-Maynooth, the Space Research Organisation of the Netherlands, Rutherford Appleton Laboratory Space, and work groups of the universities of Cambridge and Cardiff. The work of this thesis also considered the technical feasibility and design of a future space mission for the purpose of characterising Earth-type exoplanets up to 30 pc distant. This involved the establishment of the science goals and the associated technical requirements, as well as a detailed optical design of the proposed spectropolarimetric payload