A discrete-time approach to the steady-state and stability analysis of distributed nonlinear autonomous circuits

We present a direct method for the steady-state and stability analysis of autonomous circuits with transmission lines and generic non- linear elements. With the discretization of the equations that describe the circuit in the time domain, we obtain a nonlinear algebraic formulation where the unknowns to determine are the samples of the variables directly in the steady state, along with the oscillation period, the main unknown in autonomous circuits.An efficient scheme to buildtheJacobian matrix with exact partial derivatives with respect to the oscillation period and with re- spect to the samples of the unknowns is described. Without any modifica- tion in the analysis method, the stability of the solution can be computed a posteriori constructing an implicit map, where the last sample is viewed as a function of the previous samples. The application of this technique to the time-delayed Chua's circuit (TDCC) allows us to investigate the stability of the periodic solutions and to locate the period-doubling bifurcations.Peer ReviewedPostprint (published version

Steady state analysis of Chua's circuit with RLCG transmission line

In this paper we present a new technique to compute the steady state response of nonlinear autonomous circuits with RLCG transmission lines. Using multipoint Pade approximants, instead of the commonly used expansions around s=0 or s/spl rarr//spl infin/ accurate, low-order lumped equivalent circuits of the characteristic impedance and the exponential propagation function are obtained in an explicit way. Then, with the temporal discretization of the equations that describe the transformed circuit, we obtain a nonlinear algebraic formulation where the unknowns to be determined are the samples of the variables directly in the steady state, along with the oscillation period, the main unknown in autonomous circuits. An efficient scheme to build the Jacobian matrix with exact partial derivatives with respect to the oscillation period and with respect to the samples of the unknowns is obtained. Steady state solutions of the Chua's circuit with RLCG transmission line are computed for selected circuit parameters.Peer ReviewedPostprint (published version

A direct-sequence spread-spectrum super-regenerative receiver

Current applications of the super-regenerative receiver use narrowband modulations. In this paper a new architecture that allows incoherent detection of spread-spectrum signals is presented. A pseudorandom code generator has been added to the original circuit. It is clocked by the quench oscillator and takes advantage of the characteristic broad reception bandwidth. CDMA can be achieved via ASK and FSK modulated signals with high simplicity in the RF stage as well as low power consumption.Peer ReviewedPostprint (published version

A discrete-time approach to the steady-state and stability analysis of distributed nonlinear autonomous circuits

We present a direct method for the steady-state and stability analysis of autonomous circuits with transmission lines and generic nonlinear elements. With the discretization of the equations that describe the circuit in the time domain, we obtain a nonlinear algebraic formulation where the unknowns to determine are the samples of the variables directly in the steady state, along with the oscillation period, the main unknown in autonomous circuits. An efficient scheme to build the Jacobian matrix with exact partial derivatives with respect to the oscillation period and with respect to the samples of the unknowns is described. Without any modification in the analysis method, the stability of the solution can be computed a posteriori constructing an implicit map, where the last sample is viewed as a function of the previous samples. The application of this technique to the time-delayed Chua's circuit (TDCC) allows us to investigate the stability of the periodic solutions and to locate the period-doubling bifurcations.Peer ReviewedPostprint (published version

SNR measurement of superregenerative oscillators

© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper a method to measure the signal-to-noise ratio of superregenerative oscillators is presented. A spectrum analyzer can easily be coupled to a superregenerative oscillator without paying attention to possible loading effects. With just two measurements of the displayed power spectrum, in combination with the resolution bandwidth of the spectrum analyzer and the quench frequency of the oscillator, the signal-to-noise ratio is determined in a straightforward way. This is supported analytically with results from a frequency-domain analysis technique. Examples of the power displayed by a spectrum analyzer are given to provide insight into the explained procedure.Peer ReviewedPostprint (author's final draft

Monitoring and optimal management approaches to reduce water and energy consumption in milk processing processes

This paper proposes a methodology for the monitoring and optimal management of milk processing processes to reduce water and energy consumption. First, the key variables that should be measured to characterize the water/energy consumption are identified. Then, a monitoring system that is integrated with the current SCADA system already deployed in the production process has been developed that is able to evaluate the energy consumptions not directly computed from the available sensors. From real historical measurement records of the different subprocesses, their efficiency is determined. This information is used for developing an optimal management system that allows reducing the water/energy consumption. The work presented in this paper has been developed in the context of the European project named EnReMilk that aims to introduce significant water and energy in several milk processing processes by the introduction of new processing and management technologies. The assessment the proposed approach is based on the comparison with the current baseline consumptions.Peer ReviewedPostprint (author's final draft

The nonlinear class-E amplifier: a case study of harmonic balance applied to switched circuits

Nonlinear switched circuits are usually analyzed in the time domain. The use of frequency-domain methods to analyze the steady-state of switched circuits is usually restricted to linear circuits and, although Volterra series approaches are applied to the distortion of nonlinear switched circuits, the use of harmonic balance (HB) methods in nonlinear switched circuits seems to be marginal if not discarded. In this paper, we analyze the nonlinear class-E amplifier with an ideal switch by means of the HB method. We show how the switching function may be carefully chosen to improve the accuracy of the solution. When the circuit achieves actual class-E operation, the method converges better and is more accurate than classical timedomain methods. We conclude that the HB method is an alternative to time-domain methods that can be used to analyze the class-E amplifier in its expected operation mode.Postprint (published version

Gestión de proyectos TIC: modelo de formación para PYMES

La realización de proyectos en empresas es una de sus actividades fundamentales, aunque la clave de su éxito es una buena gestión. Al constatar que algunas pymes no acostumbraban a llevar a cabo una correcta gestión de los proyectos TIC, se diseñó una metodología de gestión de proyectos adecuada para este perfil de empresas y de proyectos. Aunque la metodología es clara y fácil de seguir, algunas pymes no tienen personal con una formación específica para la gestión de los proyectos. Así pues, se ha visto la necesidad de preparar un plan de formación para directivos de las pymes y otras personas implicadas en la realización y gestión de los proyectos TIC. Atendiendo al perfil de los destinatarios, la formación se deberá realizar en un tiempo limitado en el que, por un lado, se deberá convencer a los alumnos de que la metodología es fácil de utilizar y aporta ventajas respecto a la operativa utilizada y, por otro, se fomentará la participación activa, que se traducirá en la aplicación práctica, aunque sea sobre un proyecto simulado. Si la formación es adecuada, propiciará la correcta utilización de la metodología, que es el principal objetivo.Postprint (published version

A proof-of-concept superregenerative QPSK transceiver

In this paper we present a description and experimental verification of an HF-band proof-of-concept superregenerative transceiver for QPSK signals. We describe a simple implementation of an all-digital, FPGA-based, QPSK transmitter section. On the receiver side, the quench signal is generated in the same FPGA with a minimum of analog circuitry. As the main novelty, we present a simple synchronization scheme suitable for packetized transmissions.Peer ReviewedPostprint (author’s final draft

Signal and noise power spectra in superregenerative oscillators

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents a method to quantify noise in superregenerative oscillators. A frequency domain technique, originally intended to determine the signal response, can also be used to determine the noise response. This paper focuses on the procedure required to achieve this. Signal and noise spectra are obtained and their shape is compared. Finally, signal-to-noise ratio is computed for different quench signalsPeer ReviewedPostprint (author's final draft