Computationally Efficient Innovative Techniques for the Design-Oriented Simulation of Free-Running and Driven Microwave Oscillators

Analysis techniques for injection-locked oscillators/amplifiers (ILO) can be broadly divided into two classes. To the first class belong methods with a strong and rigorous theoretical basis, that can be applied to rather general circuits/systems but which are very cumbersome and/or time-consuming to apply. To the second class belong methods which are very simple and fast to apply, but either lack of validity/accuracy or are applicable only to very simple or particular cases. In this thesis, a novel method is proposed which aims at combining the rigorousness and broad applicability characterizing the first class of analysis techniques above cited with the simplicity and computational efficiency of the second class. The method relies in the combination of perturbation-refined techniques with a fundamental frequency system approach in the dynamical complex envelope domain. This permits to derive an approximate, but first-order exact, differential model of the phase-locked system useable for the steady-state, transient and stability analysis of ILOs belonging to the rather broad (and rigorously identified) class of nonlinear oscillators considered. The hybrid (analytical-numerical) nature of the formulation developed is suited for coping with all ILO design steps, from initial dimensioning (exploiting, e.g., the simplified semi-analytical expressions stemming from a low-level injection operation assumption) to accurate prediction (and fine-tuning, if required) of critical performances under high-injection signal operation. The proposed application examples, covering realistically modeled low- and high-order ILOs of both reflection and transmission type, illustrate the importance of having at one's disposal a simulation/design tool fully accounting for the deviation observed, appreciable for instance in the locking bandwidth of high-frequency circuits with respect to the simplified treatments usually applied, for a quick arrangement, in ILO design optimization procedures.Analysis techniques for injection-locked oscillators/amplifiers (ILO) can be broadly divided into two classes. To the first class belong methods with a strong and rigorous theoretical basis, that can be applied to rather general circuits/systems but which are very cumbersome and/or time-consuming to apply. To the second class belong methods which are very simple and fast to apply, but either lack of validity/accuracy or are applicable only to very simple or particular cases. In this thesis, a novel method is proposed which aims at combining the rigorousness and broad applicability characterizing the first class of analysis techniques above cited with the simplicity and computational efficiency of the second class. The method relies in the combination of perturbation-refined techniques with a fundamental frequency system approach in the dynamical complex envelope domain. This permits to derive an approximate, but first-order exact, differential model of the phase-locked system useable for the steady-state, transient and stability analysis of ILOs belonging to the rather broad (and rigorously identified) class of nonlinear oscillators considered. The hybrid (analytical-numerical) nature of the formulation developed is suited for coping with all ILO design steps, from initial dimensioning (exploiting, e.g., the simplified semi-analytical expressions stemming from a low-level injection operation assumption) to accurate prediction (and fine-tuning, if required) of critical performances under high-injection signal operation. The proposed application examples, covering realistically modeled low- and high-order ILOs of both reflection and transmission type, illustrate the importance of having at one's disposal a simulation/design tool fully accounting for the deviation observed, appreciable for instance in the locking bandwidth of high-frequency circuits with respect to the simplified treatments usually applied, for a quick arrangement, in ILO design optimization procedures

Circuit design and technological limitations of silicon RFICs for wireless applications

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 201-206).Semiconductor technologies have been a key to the growth in wireless communication over the past decade, bringing added convenience and accessibility through advantages in cost, size, and power dissipation. A better understanding of how an IC technology affects critical RF signal chain components will greatly aid the design of wireless systems and the development of process technologies for the increasingly complex applications that lie on the horizon. Many of the evolving applications will embody the concept of adaptive performance to extract the maximum capability from the RF link in terms of bandwidth, dynamic range, and power consumption-further engaging the interplay of circuits and devices is this design space and making it even more difficult to discern a clear guide upon which to base technology decisions. Rooted in these observations, this research focuses on two key themes: 1) devising methods of implementing RF circuits which allow the performance to be dynamically tuned to match real-time conditions in a power-efficient manner, and 2) refining approaches for thinking about the optimization of RF circuits at the device level. Working toward a 5.8 GHz receiver consistent with 1 GBit/s operation, signal path topologies and adjustable biasing circuits are developed for low-noise amplifiers (LNAs) and voltage-controlled oscillators (VCOs) to provide a facility by which power can be conserved when the demand for sensitivity is low. As an integral component in this effort, tools for exploring device level issues are illustrated with both circuit types, helping to identify physical limitations and design techniques through which they can be mitigated.(cont.) The design of two LNAs and four VCOs is described, each realized to provide a fully-integrated solution in a 0.5 tm SiGe BiCMOS process, and each incorporating all biasing and impedance matching on chip. Measured results for these 5-6GHz circuits allow a number of poignant technology issues to be enlightened, including an exhibition of the importance of terminal resistances and capacitances, a demonstration of where the transistor fT is relevant and where it is not, and the most direct comparison of bipolar and CMOS solutions offered to date in this frequency range. In addition to covering a number of new circuit techniques, this work concludes with some new views regarding IC technologies for RF applications.by Donald A. Hitko.Ph.D