EMC-aware analysis and design of a low-cost receiver circuit under injection locking and pulling

In low-cost receiver applications, the preselect filter is often omitted in order to reduce the footprint of the total system. However, the immunity of the receiver can be severely compromised by this approach. This paper focuses on the effects of co-located sources on the local oscillator (LO), specifically injection locking and pulling. To this end, a low-cost radio receiver (RF) front-end is designed for operation in the 2 : 4 5 GHz industrial, scientific and medical (ISM) radio band. In addition to the effects on the oscillator, the consequences on the receiver's performance are evaluated as well. For the first time in literature, this work demonstrates the critical necessity to take the potentially detrimental effects caused by injection locking and pulling into account during Electromagnetic Compatibility (EMC)-aware design

Injection locking of optomechanical oscillators via acoustic waves

Injection locking is a powerful technique for synchronization of oscillator networks and controlling the phase and frequency of individual oscillators using similar or other types of oscillators. Here, we present the first demonstration of injection locking of a radiation-pressure driven optomechanical oscillator (OMO) via acoustic waves. As opposed to previously reported techniques (based on pump modulation or direct application of a modulated electrostatic force), injection locking of OMO via acoustic waves does not require optical power modulation or physical contact with the OMO and it can easily be implemented on various platforms. Using this approach we have locked the phase and frequency of two distinct modes of a microtoroidal silica OMO to a piezoelectric transducer (PZT). We have characterized the behavior of the injection locked OMO with three acoustic excitation configurations and showed that even without proper acoustic impedance matching the OMO can be locked to the PZT and tuned over 17 kHz with only -30 dBm of RF power fed to the PZT. The high efficiency, simplicity and scalability of the proposed approach paves the road toward a new class of photonic systems that rely on synchronization of several OMOs to a single or multiple RF oscillators with applications in optical communication, metrology and sensing. Beyond its practical applications, injection locking via acoustic waves can be used in fundamental studies in quantum optomechanics where thermal and optical isolation of the OMO are critical

Review of Injected Oscillators

Oscillators are critical components in electrical and electronic engineering and other engineering and sciences. Oscillators are classified as free-running oscillators and injected oscillators. This chapter describes the background necessary for the analysis and design of injected oscillators. When an oscillator is injected by an external periodic signal mentioned as an injection signal, it is called an injected oscillator. Consequently, two phenomena occur in the injected oscillators: (I) pulling phenomena and (II) locking phenomena. For locking phenomena, the oscillation frequency of the injection signal must be near free-running oscillation frequency or its sub-/super-harmonics. Due to these phenomena are nonlinear phenomena, it is tough to achieve the exact equation or closed-form equation of them. Therefore, researchers are scrutinizing them by different analytical and numerical methods for accomplishing an exact inside view of their performances. In this chapter, injected oscillators are investigated in two main subjects: first, analytical methods on locking and pulling phenomena are reviewed, and second, applications of injected oscillators are reviewed such as injection-locked frequency dividers at the latter. Furthermore, methods of enhancing the locking range are introduced

Effects of noisy and modulated interferers on the free-running oscillator spectrum

A new methodology for the prediction of oscillator phase dynamics under the effect of an interference signal is presented. It is based on a semianalytical formulation in the presence of a noisy or modulated interferer, using a realistic oscillator model extracted from harmonic-balance simulations. The theoretical analysis of the phase process enables the derivation of key mathematical properties, used for an efficient calculation of the interfered-oscillator spectrum. The resulting quasi-periodic spectrum is predicted, as well as the impact of the interferer phase noise and modulation over each spectral component, in particular over the one at the fundamental frequency. It is demonstrated that under some conditions, the phase noise at this component is pulled to that of the interference signal. Resonance effects at multiples of the beat frequency are also predicted. In addition, the effects of interferer phase and amplitude modulation on the oscillator phase dynamics have been studied and compared. For that analysis, efficient simulation techniques have been developed. The analyses have been validated with experimental measurements in an FET-based oscillator at 2.5 GHz, obtaining excellent agreement.This work was supported in part by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF/FEDER) under research projects TEC2014-60283-C3-1-R and TEC2017-88242-C3-1-R, in part by the Juan de la Cierva Research Program under Grant IJCI-2014-19141, and in part by the Parliament of Cantabria through the project Cantabria Explora under Grant 12.JP02.6406

Two-scale envelope-domain analysis of injected chirped oscillators

The response of chirped oscillators under the injection of independent signals, for spectrum sensing in cognitive radio, and under self-injection, for radio frequency identification, is analyzed in detail. The investigation is performed by means of a semianalytical formulation, based on a realistic modeling of the free-running oscillator, extracted from harmonic-balance simulations or from experimental measurements, through a new characterization technique. In the new formulation, the oscillator is linearized about a free-running solution that varies with the control voltage. This enables its application to oscillators having a frequency characteristic that deviates from the linear one. In the case of injection by independent signals, the two-scale envelope-domain formulation will enable an efficient handling of the difference between the slow chirp frequency and the beat frequency. The input carriers can be detected from their dynamic synchronization intervals or, at lower input-power levels, from the dynamics of the beat frequency. Noise perturbations are introduced into the formulation, which enables an estimation of the minimum detectable signal. In the case of a self-injected oscillator for radio frequency identification, an insightful formulation is derived to predict the propagation and tag-resonance effects on the instantaneous oscillation frequency. The tag-resonance signature gives rise to a distinct modulation of the oscillation frequency during the chirp period, which can be detected from the variation of the oscillator bias current. The analysis methods are illustrated through their application to a chirped oscillator, operating in the band 2-3 GHz.This work was supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF/FEDER) under Project TEC2014-60283-C3-1-R and Project TEC2017-88242-C3-1-

Wireless-coupled oscillator systems with an injection-locking signal

A detailed analysis of wireless-coupled oscillator systems under the effect of an injection-locking signal is presented. The injection source of high spectral purity is introduced at a single node and enables a reduction of the phase-noise spectral density. Under this injection source, the behavior of the coupled system is qualitatively different from the one obtained in free-running conditions. Two cases are considered: bilateral synchronization, in which an independent source is connected to a particular system oscillator, coupled to the other oscillator elements, and unilateral synchronization, in which one of these elements is replaced by an independent source that cannot be influenced by the rest. The two cases are illustrated through the analysis of a wireless-coupled system with a star topology, such that the injection signal is introduced at the central node. The investigation involves an insightful analytical calculation of the coexisting steady-state solutions, as well as a determination of their stability and bifurcation properties and phase noise. The injection signal stabilizes the system in a large and continuous distance interval, enabling a more robust operation than in autonomous (noninjected) conditions. A coupled system operating at 2.45 GHz has been manufactured and experimentally characterized, obtaining a very good agreement between simulations and measurements.This work was supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF/FEDER) under research projects TEC2014-60283-C3-1-R and TEC2017-88242-C3-1-R

Analysis of the high frequency substrate noise effects on LC-VCOs

La integració de transceptors per comunicacions de radiofreqüència en CMOS pot quedar seriosament limitada per la interacció entre els seus blocs, arribant a desaconsellar la utilització de un únic dau de silici. El soroll d’alta freqüència generat per certs blocs, com l’amplificador de potencia, pot viatjar pel substrat i amenaçar el correcte funcionament de l’oscil·lador local. Trobem tres raons importants que mostren aquest risc d’interacció entre blocs i que justifiquen la necessitat d’un estudi profund per minimitzar-lo. Les característiques del substrat fan que el soroll d’alta freqüència es propagui m’és fàcilment que el de baixa freqüència. Per altra banda, les estructures de protecció perden eficiència a mesura que la freqüència augmenta. Finalment, el soroll d’alta freqüència que arriba a l’oscil·lador degrada al seu correcte comportament. El propòsit d’aquesta tesis és analitzar en profunditat la interacció entre el soroll d’alta freqüència que es propaga pel substrat i l’oscil·lador amb l’objectiu de poder predir, mitjançant un model, l’efecte que aquest soroll pot tenir sobre el correcte funcionament de l’oscil·lador. Es volen proporcionar diverses guies i normes a seguir que permeti als dissenyadors augmentar la robustesa dels oscil·ladors al soroll d’alta freqüència que viatja pel substrat. La investigació de l’efecte del soroll de substrat en oscil·ladors s’ha iniciat des d’un punt de vista empíric, per una banda, analitzant la propagació de senyals a través del substrat i avaluant l’eficiència d’estructures per bloquejar aquesta propagació, i per altra, determinant l’efecte d’un to present en el substrat en un oscil·lador. Aquesta investigació ha mostrat que la injecció d’un to d’alta freqüència en el substrat es pot propagar fins arribar a l’oscil·lador i que, a causa del ’pulling’ de freqüència, pot modular en freqüència la sortida de l’oscil·lador. A partir dels resultats de l’anàlisi empíric s’ha aportat un model matemàtic que permet predir l’efecte del soroll en l’oscil·lador. Aquest model té el principal avantatge en el fet de que està basat en paràmetres físics de l’oscil·lador o del soroll, permetent determinar les mesures que un dissenyador pot prendre per augmentar la robustesa de l’oscil·lador així com les conseqüències que aquestes mesures tenen sobre el seu funcionament global (trade-offs). El model ha estat comparat tant amb simulacions com amb mesures reals demostrant ser molt precís a l’hora de predir l’efecte del soroll de substrat. La utilitat del model com a eina de disseny s’ha demostrat en dos estudis. Primerament, les conclusions del model han estat aplicades en el procés de disseny d’un oscil·lador d’ultra baix consum a 2.5GHz, aconseguint un oscil·lador robust al soroll de substrat d’alta freqüència i amb característiques totalment compatibles amb els principals estàndards de comunicació en aquesta banda. Finalment, el model s’ha utilitzat com a eina d’anàlisi per avaluar la causa de les diferències, en termes de robustesa a soroll de substrat, mesurades en dos oscil·ladors a 60GHz amb dues diferents estratègies d’apantallament de l’inductor del tanc de ressonant, flotant en un cas i connectat a terra en l’altre. El model ha mostrat que les diferències en robustesa són causades per la millora en el factor de qualitat i en l’amplitud d’oscil·lació i no per un augment en l’aïllament entre tanc i substrat. Per altra banda, el model ha demostrat ser vàlid i molt precís inclús en aquest rang de freqüència tan extrem. el principal avantatge en el fet de que està basat en paràmetres físics de l’oscil·lador o del soroll, permetent determinar les mesures que un dissenyador pot prendre per augmentar la robustesa de l’oscil·lador així com les conseqüències que aquestes mesures tenen sobre el seu funcionament global (trade-offs). El model ha estat comparat tant amb simulacions com amb mesures reals demostrant ser molt precís a l’hora de predir l’efecte del soroll de substrat. La utilitat del model com a eina de disseny s’ha demostrat en dos estudis. Primerament, les conclusions del model han estat aplicades en el procés de disseny d’un oscil·lador d’ultra baix consum a 2.5GHz, aconseguint un oscil·lador robust al soroll de substrat d’alta freqüència i amb característiques totalment compatibles amb els principals estàndards de comunicació en aquesta banda. Finalment, el model s’ha utilitzat com a eina d’anàlisi per avaluar la causa de les diferències, en termes de robustesa a soroll de substrat, mesurades en dos oscil·ladors a 60GHz amb dues diferents estratègies d’apantallament de l’inductor del tanc de ressonant, flotant en un cas i connectat a terra en l’altre. El model ha mostrat que les diferències en robustesa són causades per la millora en el factor de qualitat i en l’amplitud d’oscil·lació i no per un augment en l’aïllament entre tanc i substrat. Per altra banda, el model ha demostrat ser vàlid i molt precís inclús en aquest rang de freqüència tan extrem.The integration of transceivers for RF communication in CMOS can be seriously limited by the interaction between their blocks, even advising against using a single silicon die. The high frequency noise generated by some of the blocks, like the power amplifier, can travel through the substrate, reaching the local oscillator and threatening its correct performance. Three important reasons can be stated that show the risk of the single die integration. Noise propagation is easier the higher the frequency. Moreover, the protection structures lose efficiency as the noise frequency increases. Finally, the high frequency noise that reaches the local oscillator degrades its performance. The purpose of this thesis is to deeply analyze the interaction between the high frequency substrate noise and the oscillator with the objective of being able to predict, thanks to a model, the effect that this noise may have over the correct behavior of the oscillator. We want to provide some guidelines to the designers to allow them to increase the robustness of the oscillator to high frequency substrate noise. The investigation of the effect of the high frequency substrate noise on oscillators has started from an empirical point of view, on one hand, analyzing the noise propagation through the substrate and evaluating the efficiency of some structures to block this propagation, and on the other hand, determining the effect on an oscillator of a high frequency noise tone present in the substrate. This investigation has shown that the injection of a high frequency tone in the substrate can reach the oscillator and, due to a frequency pulling effect, it can modulate in frequency the output of the oscillator. Based on the results obtained during the empirical analysis, a mathematical model to predict the effect of the substrate noise on the oscillator has been provided. The main advantage of this model is the fact that it is based on physical parameters of the oscillator and of the noise, allowing to determine the measures that a designer can take to increase the robustness of the oscillator as well as the consequences (trade-offs) that these measures have over its global performance. This model has been compared against both, simulations and real measurements, showing a very high accuracy to predict the effect of the high frequency substrate noise. The usefulness of the presented model as a design tool has been demonstrated in two case studies. Firstly, the conclusions obtained from the model have been applied in the design of an ultra low power consumption 2.5 GHz oscillator robust to the high frequency substrate noise with characteristics which make it compatible with the main communication standards in this frequency band. Finally, the model has been used as an analysis tool to evaluate the cause of the differences, in terms of performance degradation due to substrate noise, measured in two 60 GHz oscillators with two different tank inductor shielding strategies, floating and grounded. The model has determined that the robustness differences are caused by the improvement in the tank quality factor and in the oscillation amplitude and no by an increased isolation between the tank and the substrate. The model has shown to be valid and very accurate even in these extreme frequency range.Postprint (published version