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

Creació de materials docents per assignatures de telecomunicacions amb eines informàtiques de fàcil utilització

Seguint l’enfocament de l’Espai Europeu d’Educació Superior (EEES), on es valora l’aprenentatge cooperatiu i basat en projectes, es troba interessant disposar de materials docents, per al treball individual o col·lectiu, en dues de les assignatures de l’Enginyeria Tècnica de Telecomunicacions que s’ofereix a l’EPSEM. El treball realitzat es divideix en diverses fases. En primer lloc, s’ha preparat la informació que es desitja transmetre als alumnes, per agrupar-la després en blocs temàtics. Amb aquesta informació ja estructurada, s’han començat a entrar les dades. Un cop realitzats aquests passos, es pot crear, de manera fàcil, la presentació flash, ja que l’aplicació disposa d’una opció amb aquesta finalitat. Aquesta presentació es pot guardar i utilitzar en qualsevol moment i lloc. El principal resultat ha estat la obtenció de materials docents interactius, disponibles en suport informàtic, amb text i gràfics, pels quals es pot navegar fàcilment i còmoda, per a dues assignatures de la titulació de telecomunicacions.Peer ReviewedPostprint (published version

Forward backward asymmetries of lepton pairs in events with a large transverse momentum jet at hadron colliders

We discuss forward-backward charge asymmetries for lepton-pair production in association with a large-transverse-momentum jet at hadron colliders. The lepton charge asymmetry relative to the jet direction AjFB gives a new determination of the effective weak mixing angle sin2lept eff M2 Z with a statistical precision after cuts of 10 3 (8 10 3) at LHC (Tevatron). This is to be compared with the current uncertainty at LEP and SLD from the asymmetries alone, 2 10 4. The identification of b jets also allows for the measurement of the bottom-quark–Z asymmetry AbFB at hadron colliders, the resulting statistical precision for sin2lept eff M2 Z being 9 10 4 (2 10 2 at Tevatron), also lower than the reported precision at e+ e- colliders, 3 10 -4.Peer ReviewedPostprint (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

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

Joint symbol and chip synchronization for a burst-mode-communication superregenerative MSK receiver

In this paper we describe a superregenerative (SR) MSK receiver able to operate in a burst-mode framework where synchronization is required for each packet. The receiver is based on an SR oscillator which provides samples of the incoming instantaneous phase trajectories. We develop a simple yet effective technique to achieve joint chip and symbol synchronization within the time limits of a suitable preamble. We develop some general results and focus on the case of the IEEE 802.15.4 MSK physical layer. We provide details on a VHDL implementation on an FPGA where the most complex digital processing block is an accumulator. Simulation and experimental results are provided to validate the described technique.Peer ReviewedPostprint (published version

Sub-nanosecond pulse filtering and amplification through firts-order controlled circuit instability

In this paper we investigate how to use controlled circuit instability in the filtering and amplification of narrow pulses. The basic circuit consists of a first-order RC network coupled to a negative resistance controlled by an external quench generator, which yields alternating periods of stability and instability. The study shows that when the circuit acts as a signal generator it can produce narrow exponential or Gaussian pulses, depending on the quench waveform applied. Included as a receiver front end, the circuit behaves as a highgain narrow-pulse filter. We also estimate the circuit parameters required to generate and receive sub-nanosecond pulses.Postprint (published version

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

A BPSK superregenerative receiver. Preliminary results

This paper describes a bit-synchronous superregenerative receiver suitable for BPSK demodulation. The output of the superregenerative oscillator (SRO), which reproduces the phase information of the input signal, is directly sampled by a D flip flop clocked by a signal derived from the quench waveform. Analytical background on the response of the SRO to a BPSK modulated input is presented. A PSpice macromodel of the receiver is also provided, allowing simulation in the linear and logarithmic modes of operation. Simulation results confirm the feasibility of the described approach. Finally, a proof-of-concept superregenerative receiver, capable of receiving a BPSK modulated carrier at 27 MHz with preliminary experimental results is presented. The measured sensitivity of this receiver is –99.5 dBm for a bit error rate of 10-3..Postprint (published version

Superregeneration revisited: from principles to current applications

© 2020 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.Wireless communications play a central role in our modern connected lives; at the same time, they constitute a very broad and deep area of research. The elements that make wireless communications possible are a transmitter, which sends information through electromagnetic waves; a medium that is able to transport these waves; and, finally, a receiver, which extracts the information from the-usually very small-amount of energy it is able to collect from the medium.Peer ReviewedPostprint (author's final draft