113 research outputs found
Circuiti e sottosistemi a microonde e onde millimetriche per ricevitori a basso rumore e antenne intelligenti
No full textQuesto lavoro affronta gli aspetti riguardanti le metodologie e tecniche di analisi e progettazione per alcune funzionalità in front-end ricevitori a radiofrequenza ad elevata sensibilità e riconfigurabili. Tali funzionalità sono: l’amplificazione a basso rumore e il controllo dell’ampiezza di un segnale a RF. Infine, un’ulteriore investigazione ha focalizzato gli aspetti e le criticità in circuiti multi-funzione a elevata integrazione.
E’ stata mostrata una metodologia per progettazione di amplificatori a basso rumore a microonde che ha portato a definire le relazioni di adattamento simultaneamente ottenibile in ingresso e uscita in un LNA. Il principale risultato di tale investigazione è l’individuazione di un grafico che permette di valutare in modo sinottico il guadagno di trasduzione e gli adattamenti I/O di una rete 2-porte amplificatrice una volta fissata l’impedenza di sorgente, e quindi il fattore di rumore del LNA.
Sull’argomento degli amplificatori a basso rumore a onde millimetriche, è stato proposto un insieme di metodi analitici e sintetici che coprono le tematiche dalla scelta della tecnologia del dispositivo attivo al test del LNA realizzato. E’ stato ripreso il significato della Misura di Rumore nella progettazione a basso rumore a onde millimetriche investigando anche le tematiche della simulazione EM planare e 3D a onde millimetriche.
All’interno della tematica sul controllo dell’ampiezza di un segnale a RF è stato investigato in profondità lo sfasamento parassita connesso al cambio di stato in attenuatori digitali a commutazione. E’ stata suggerita una tecnica circuitale e sono state ricavate equazioni di progetto che permettono di compensare tale sfasamento indesiderato, fornendo una relazione che consente di dimensionare l’elemento reattivo che compensa tale effetto sgradito.
Infine, sulla materia della progettazione di circuiti-multi funzione a elevata integrazione è stata investigata la realizzabilità di un modulo contenente diverse funzionalità: controllo dell’ampiezza del segnale, amplificazione, scelta del modo T/R, controllo della fase del segnale e conversione seriale/parallelo dei dati di comando. Sono state presentate le procedure di progetto di alcuni sottosistemi nonché i criteri e i passi seguiti nella fase di integrazione.This work deals with aspects relating to analysis and design methodologies and techniques for some circuits in high sensitivity and reconfigurable front-end RF receivers. These circuits are: low noise amplifier and RF attenuators. Finally, further investigation has focused aspects and issues of multi-function high integration circuits.
A methodology for designing microwave low noise amplifiers is reported. The latter has led to define the I/O matching relationships simultaneously achievable in an LNA. The main result of this investigation is the identification of a chart that allows to synoptically evaluating the achievable gain and I/O matching of a 2-port amplifier, once the source impedance is fixed and consequently the LNA noise factor.
A set of analytical and synthetic methods on millimetre wave low noise amplifiers has been proposed, covering topics from the active device technology selection to test the realized LNA. The meaning of the noise measure parameter is reprised for designing millimetre wave low-noise. The issues of and 3D planar EM millimetre wave simulation is also investigated.
The parasitic phase shift in digital attenuators has been investigated in depth. Such parasitic effect is related to the change of state in digital switched attenuators. A technique has been suggested and circuit equations were derived that allow to compensate such unwanted phase shift, providing design relations that allows to estimate the value of the reactive element that compensates for this undesirable effect.
Finally, in the field of multi-function high-integration circuits design, the feasibility of a module containing several functionalities has been investigated. The latter are: control of the signal amplitude, amplification, selection of Tx/Rx mode, control the phase of the signal and serial to parallel control data conversion. The design procedures of some sub-modules, together with the criteria and the steps followed in the process of integration, have been reported
Design of a MMIC low-noise amplifier in industrial gallium arsenide technology for E-band 5G transceivers
No full textThe technology, design procedure and measurements of an E-band (71-86 GHz) high performance gallium arsenide (GaAs) low-noise amplifier (LNA) are presented. The latter provides a gain in excess of 20 dB, an average in-band noise figure (NF) of 2.3 dB, absorbing 60 mW DC bias power. A European space-qualified technology (OMMIC's GaAs 70 nm process) has been selected to demonstrate the feasibility of employing the proposed LNA for production-ready wireless backhaul point-to-point communication systems. A possible installation scenario has been depicted, in order to verify the maximum distance at which TX and RX antennas can be placed and employing the proposed LNA as first amplifying stage of the receiver chain
5-55 GHz Watt-level Gallium Nitride Stacked FET Travelling-Wave Power Amplifier
No full textTwo well-known ultra wide-band topologies, the travelling-wave amplifier and the stacked cell, are gainfully employed to demonstrate a decade bandwidth behaviour (5-55 GHz) in conjunction with watt-level saturated output power. The selected technology is OMMIC’s Gallium Nitride on Silicon, featuring the possibility to simultaneously insert 60-nm and 100-nm gate length FETs in the same MMIC
Ultralow-Power Digital Control and Signal Conditioning in GaAs MMIC Core Chip for X-Band AESA Systems
No full textThis work presents the design and characterization of an ultralow-power core chip for electronically scanned arrays at X-band, implemented in 0.25-/0.5-μm E-/D-mode gallium arsenide (GaAs) pHEMT technology. In particular, design details are given about the two core functional blocks embedded in the microwave monolithic integrated circuit (MMIC): a 12-bit phase and amplitude control circuit and an 18-bit serial-to-parallel (S2P) interface. The S2P interface was designed resorting to a custom symmetric device model, expressly conceived for the time-domain simulations required for digital circuits. Due to the adoption of a differential structure with resistive pull-ups, it achieves a state-of-the-art power consumption of 2.2 mW/bit and nearly 87% yield. The analog circuit includes a 6-bit phase shifter (PS) and a 6-bit attenuator. To mitigate risks, two different PS architectures have been developed and are compared in this work, discussing advantages and drawbacks of the different solutions. Since the two designs share the same target specifications, a truly fair comparison can be made not only in terms of performance but also concerning robustness and repeatability, thus providing useful guidelines for the selection of the most appropriate strategy. In particular, it is shown that one architecture outperforms the other by about 2 dB and 1.5° in terms of insertion loss and rms phase error, respectively
Noise factor of a transmission line subjected to thermal gradients
No full textA novel, analytical treatment of noise factor in ideal transmission lines subjected to thermal gradients is presented. Temperature dependence on the propagation direction is assumed linear, whereas line loss is initially considered constant. The latter restriction is then removed, in such a manner that, for the first time in the literature, linearly varying line losses are also addressed. In both cases, closed formulae are presented allowing to compute line noise factor for arbitrary source terminations. Previous numerical implementations of the underlying theory are also reappraised both as an introduction to the Reader and as a test bench of the closed-form results. A discussion of the effects of a non-uniform temperature distribution across the transverse section of the transmission line is provided upfront, so as to clarify the conditions under which the usual simplifications are valid. This discussion too is believed by the Authors to be original
MMIC LNAs for radioastronomy applications using advanced industrial 70 nm metamorphic technology
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