It is widely believed that many drawbacks in today's wireless communication paradigm might be relieved by enabling high carrier frequency transmission, and endowing both the network and the user equipment with some degree of reconfigurability. The urgency of a new
framework in wireless digital transmission which should allow for higher bit rate, lower latency and tighter delay constraints, led us to investigate the fundamental building blocks which, at the circuital/device level, will foster a change towards more efficient communication schemes, delivering a more satisfactory end user experience.
Specifically, this work deals with the inherently analog devices, found at the core of each transceiver module and capable of providing the carrier signal; these are the oscillators. In particular, two distinct classes of oscillators are regarded central to our contribution. One class is
constituted by N-push oscillators, which thanks to coupling effect of N identical core oscillators allow N-fold harmonic generation (and thus high frequency transmission). The second class is constituted by wideband tunable oscillators, whose topology derives from a feedback distributed amplifier and therefore called distributed oscillators; by adequately altering the bias level at each section Distributed Voltage Controlled Oscillators can be implemented (which can scan a wide frequency range). The introductory part of this work, deals with their operation principles in great detail.
As microwave oscillators are nonlinear devices, a full nonlinear analysis, synthesis, and optimization is considered for their implementation. Consequently, nonlinear numerical techniques have been reviewed in the second part of the thesis. Particularly, the role of Harmonic
Balance simulations and the auxiliary generator/probe method for obtaining the oscillator solutions has been emphasized; the overall research goal of this dissertation is to show that the former techniques are very effective in obtaining detailed information about the periodic steady state behavior for the two class of circuits being investigated.
A triple-push oscillator topology has been initially considered. Provided a certain phase distribution is maintained among the oscillating elements, the output power of the third harmonic increases while the lower order harmonics cancel out, which represents the default operating mode. Due to circuit symmetry, to the presence of delay in the coupling network and to unavoidable mismatches, unwanted oscillating modes might coexist with the intended one. A design strategy relying on the Harmonic Balance parametric analysis of the oscillating voltage at a selected node in the coupling network with respect to coupling phase and coupling strength is presented, to the aim of quenching undesired oscillation modes. Moreover the design of a four stage reverse mode distributed voltage controlled oscillator
(DVCO) has been described. All the design steps have been reported, from a very idealized, purely behavioral design to a very concrete one, involving details derived from electromagnetic simulations. Harmonic Balance techniques were used to evaluate its tuning function, output power and DC current consumption, which have been completely characterized across the tuning bandwidth. Finally, a method for an optimized design with reduced variations in the output power has been presented. An alternative implementation, targeting wider tuning ranges/ higher oscillation frequencies was introduced. The measurements performed on the fabricated prototypes revealed good agreement with the simulation results, confirming the validity of the approach.
| Identifer | oai:union.ndltd.org:TDX_UPC/oai:www.tdx.cat:10803/128791 |
| Date | 30 July 2013 |
| Creators | Acampora, Alessandro |
| Contributors | Georgiadis, Apostolos, Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions |
| Publisher | Universitat Politècnica de Catalunya |
| Source Sets | Universitat Politècnica de Catalunya |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:eu-repo/semantics/publishedVersion |
| Format | 244 p., application/pdf |
| Source | TDX (Tesis Doctorals en Xarxa) |
| Rights | info:eu-repo/semantics/openAccess, ADVERTIMENT. L'accés als continguts d'aquesta tesi doctoral i la seva utilització ha de respectar els drets de la persona autora. Pot ser utilitzada per a consulta o estudi personal, així com en activitats o materials d'investigació i docència en els termes establerts a l'art. 32 del Text Refós de la Llei de Propietat Intel·lectual (RDL 1/1996). Per altres utilitzacions es requereix l'autorització prèvia i expressa de la persona autora. En qualsevol cas, en la utilització dels seus continguts caldrà indicar de forma clara el nom i cognoms de la persona autora i el títol de la tesi doctoral. No s'autoritza la seva reproducció o altres formes d'explotació efectuades amb finalitats de lucre ni la seva comunicació pública des d'un lloc aliè al servei TDX. Tampoc s'autoritza la presentació del seu contingut en una finestra o marc aliè a TDX (framing). Aquesta reserva de drets afecta tant als continguts de la tesi com als seus resums i índexs. |
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