Design and analysis of fully integrated differential VCOs

Oscillators play a decisive role for electronic equipment in many fields-like communication, navigation or data processing. Especially oscillators are key building blocks in integrated transceivers for wired and wireless communication systems. In this context the study of fully integrated differential VCOs has received attention. In this paper we present an analytic analysis of the steady state oscillation of integrated differential VCOs which is based on a nonlinear model of the oscillator. The outcomes of this are design formulas for the amplitude as well as the stability of the oscillator which take the nonlinearity of the circuit into account. © 2005 Copernicus GmbH

A design approach for integrated CMOS LC-tank oscillators using bifurcation analysis

Electrical oscillators play a decisive role in integrated transceivers for wired and wireless communication systems. In this context the study of fully integrated differential VCOs has received attention. In this paper formulas for investigations of the stability as well as the amplitude of CMOS LC tank oscillators are derived, where an overall model of nonlinear gain elements is used. By means of these results we are able to present an improved design approach which gives a deeper insight into the functionality of LC tank VCOs

Nichtlineare Analyse von LC-TANK VCOs unter Berücksichtigung parasitärer Substrateffekte

In dieser Arbeit wird ein Konzept vorgestellt, die Schaltungsarchitektur des LC-Tank-VCOs im höherdimensionalen Zustandsraum zu modellieren. Dabei wurde die VCO-Schaltung auf dominante nichtlineare und asymmetrische Effekte näher untersucht. Das entwickelte Modell bildet die Grundlage für nachfolgende parameterabhängige Analysen der Oszillatorschaltung mittels der Andronov-Hopf Bifurkationsanalyse. Zu diesem Zweck wurde ein höherdimensionales Modell entwickelt, welches für die Bifurkationsanalyse auf ein System 2. Ordnung reduziert werden muss. Als mathematisches Hilfsmittel zur Ordnungsreduktion des Systems wird das Verfahren der Zentrumsmannigfaltigkeit verwendet. Das Differentialgleichungssystem wird sehr schaltungsnah aufgestellt, daraus resultiert der Vorteil einer genaueren Repräsentation des physikalischen Verhaltens der Schaltung. Ziel ist es möglichst viele Effekte die sich auf das Verhalten des VCOs auswirken können, mit zu berücksichtigen

Demonstration of fully integrated parity-time-symmetric electronics

Harnessing parity-time (PT) symmetry with balanced gain and loss profiles has created a variety of opportunities in electronics from wireless energy transfer to telemetry sensing and topological defect engineering. However, existing implementations often employ ad-hoc approaches at low operating frequencies and are unable to accommodate large-scale integration. Here, we report a fully integrated realization of PT-symmetry in a standard complementary metal-oxide-semiconductor technology. Our work demonstrates salient PT-symmetry features such as phase transition as well as the ability to manipulate broadband microwave generation and propagation beyond the limitations encountered by exiting schemes. The system shows 2.1 times bandwidth and 30 percentage noise reduction compared to conventional microwave generation in oscillatory mode and displays large non-reciprocal microwave transport from 2.75 to 3.10 gigahertz in non-oscillatory mode due to enhanced nonlinearities. This approach could enrich integrated circuit (IC) design methodology beyond well-established performance limits and enable the use of scalable IC technology to study topological effects in high-dimensional non-Hermitian systems.Comment: 52 pages (16 pages Main Text, 28 pages Supplementary Materials, 4 pages reference), 27 figures (4 figures Main Text, 23 figures Supplementary Materials), 93 references (50 references Main Text, 43 references Supplementary Materials

Integrated RF oscillators and LO signal generation circuits

This thesis deals with fully integrated LC oscillators and local oscillator (LO) signal generation circuits. In communication systems a good-quality LO signal for up- and down-conversion in transmitters is needed. The LO signal needs to span the required frequency range and have good frequency stability and low phase noise. Furthermore, most modern systems require accurate quadrature (IQ) LO signals. This thesis tackles these challenges by presenting a detailed study of LC oscillators, monolithic elements for good-quality LC resonators, and circuits for IQ-signal generation and for frequency conversion, as well as many experimental circuits. Monolithic coils and variable capacitors are essential, and this thesis deals with good structures of these devices and their proper modeling. As experimental test devices, over forty monolithic inductors and thirty varactors have been implemented, measured and modeled. Actively synthesized reactive elements were studied as replacements for these passive devices. At first glance these circuits show promising characteristics, but closer noise and nonlinearity analysis reveals that these circuits suffer from high noise levels and a small dynamic range. Nine circuit implementations with various actively synthesized variable capacitors were done. Quadrature signal generation can be performed with three different methods, and these are analyzed in the thesis. Frequency conversion circuits are used for alleviating coupling problems or to expand the number of frequency bands covered. The thesis includes an analysis of single-sideband mixing, frequency dividers, and frequency multipliers, which are used to perform the four basic arithmetical operations for the frequency tone. Two design cases are presented. The first one is a single-sideband mixing method for the generation of WiMedia UWB LO-signals, and the second one is a frequency conversion unit for a digital period synthesizer. The last part of the thesis presents five research projects. In the first one a temperature-compensated GaAs MESFET VCO was developed. The second one deals with circuit and device development for an experimental-level BiCMOS process. A cable-modem RF tuner IC using a SiGe process was developed in the third project, and a CMOS flip-chip VCO module in the fourth one. Finally, two frequency synthesizers for UWB radios are presented

Sliding-mode amplitude control techniques for harmonic oscillators

This thesis investigates both theoretical and implementation-level aspects of switching- feedback control strategies for the development of voltage-controlled oscillators. We use a modified sliding-mode compensation scheme based on various norms of the system state to achieve amplitude control for wide-tuning range oscillators. The proposed controller provides amplitude control at minimal cost in area and power consumption. Verification of our theory is achieved with the physical realization of an amplitude controlled negative-Gm LC oscillator. A wide-tuning range RF ring oscillator is developed and simulated, showing the effectiveness of our methods for high speed oscillators. The resulting ring oscillator produces an amplitude controlled sinusoidal signal operating at frequencies ranging from 170 MHz to 2.1 GHz. Total harmonic distortion is maintained below 0:8% for an oscillation amplitude of 2 Vpp over the entire tuning range. Phase noise is measured as -105.6 dBc/Hz at 1.135 GHz with a 1 MHz offset

Complex dynamics of a microwave time-delayed feedback loop

The subject of this thesis is deterministic behaviors generated from a microwave time-delayed feedback loop. Time-delayed feedback systems are especially interesting because of the rich variety of dynamical behaviors that they can support. While ordinary differential equations must be of at least third-order to produce chaos, even a simple first-order nonlinear delay differential equation can produce higher-dimensional chaotic dynamics. The system reported in the thesis is governed by a very simple nonlinear delay differential equation. The experimental implementation uses both microwave and digital components to achieve the nonlinearity and time-delayed feedback, respectively. When a sinusoidal nonlinearity is incorporated, the dynamical behaviors range from fixed-point to periodic to chaotic depending on the feedback strength. The microwave frequency modulated chaotic signal generated by this system offers advantages in range and velocity sensing applications. When the sinusoidal nonlinearity is replaced by a binary nonlinearity, the system exhibits a complex periodic attractor with no fixed-point solution. Although there are many classic electronic circuits that produce chaotic behavior, microwave sources of chaos are especially relevant in communication and sensing applications where the signal must be transmitted between locations. The system also can exhibit random walk behavior when being operated in a higher feedback strength regime. Depending on the feedback strength values, the random behaviors can have properties of a regular or fractional Brownian motion. By unidirectional coupling two systems in the baseband, envelope synchronization between two deterministic Brownian motions can be achieved

Kytketyt MEMS-resonaattoriverkot

Micromechanical resonance frequencies are in a standard manner a few tens of MHz and can even cover the requency range up to a few GHz. When using high quality material such as quartz of silicon, also internal losses are very low. By physical coupling of resonators into a network, one can realize various mechanical signal processing, filtering or for example neural network type behavior. Since coupling between resonators are realized by some kind of bridge, which can be either rather linear or alternatively intentionally very nonlinear, the overall behavior of the whole network is very complex. Of general interest are effects that originate from multiple inputs and outputs and which could lead to a rather unexpected spectral or transient behavior of the signals, which can be found by computer modelling.Mikromekaaniset resonanssitaajuudet ovat tyypillisesti muutamia kymmeniä megahertsejä mutta voivat kattaa taajuuskaistan aina muutamiin gigahertseihin asti. Käytettäessä korkealaatuisia materiaaleja kuten kvartsia tai piitä myös signaalin häviöt ovat erittäin pieniä. Kytkemällä resonaattoreita fyysiseksi verkoksi voidaan mekaanisilla rakenteilla suorittaa signaalinkäsittelyä, realisoida suodattimia ja jopa neuroverkkoja. Koska yksittäisten resonaattorien välinen kytkentä on jonkinlainen silta, joka voi olla joko melko lineaarinen tai vaihtoehtoisesti tarkoituksellisesti erittäin epälineaarinen, on koko verkon käyttäytyminen erittäin monimutkaista. Yleisesti kiinnostavia ovat useista sisäänmenoista ja ulostuloista johtuvat ilmiöt, jotka voivat johtaa signaalien spektrin tai transienttivasteen melko odottamattomaan tai epäintuitiiviseen käyttäytymiseen, jonka voi löytää ja tulkita tietokonesimulaatioilla