Interference of Spread-Spectrum Switching-Mode Power Converters and Low-Frequency Digital Lines

The interference between switching mode power converters and wireline digital communications is addressed in this paper and the impact on communication errors of different Spread Spectrum (SS) modulation techniques, which are commonly used in power convertors to comply with EMC regulations, is experimentally investigated in a particular case. Experimental results do not highlight significant differences in terms of communication error rate induced in the victim data line between power converters featuring conventional and SS pulse width modulations

Correlation Length and Universality in the BCS-BEC Crossover for Energy-Dependent Resonance Superfluidity

We consider the BCS-BEC crossover of a quantum Fermi gas at T = 0 in the presence of an energy-dependent Fano-Feshbach resonance, driving the system from broad to narrow limits.We choose a minimal microscopic potential reproducing the two-particle resonance physics in terms of the scattering length a and the eective range R representing the resonance width, and solve the BCS mean-eld equations varying a, R and the density. We show that the chemical potential and the condensate fraction manifest an universal behavior when the correlation length, measuring the pair size, is used as the crossover parameter. These results can be useful in view of the more recent perspectives of realizing narrow resonances also by optical means and amenable as a base Quantum Monte Carlo simulations

Interference of Periodic and Spread-Spectrum-Modulated Waveforms with Analog and Digital Communications

In this article, the effectiveness and the limitations of spread-spectrum (SS) modulation techniques employed in switching-mode power converters and in digital systems to mitigate interference with communication equipment are analyzed and discussed under the EMC standard perspective and under an information theoretical perspective, with reference to different real-world scenarios. Substantial difference between potential EMI issues in traditional analog radio/TV broadcasting, digital data lines, and digital links featuring advanced channel coding techniques, e.g. in emerging power line communication (PLC) systems, are highlighted. Practical recommendations on the adoption of SS modulations along with a general reflection on the evolution of EMC requirements are finally given

Sensitivity of Equivalent Circuits on the Extraction Procedure

The present paper proposes an approach to evaluate the “quality” of equivalent circuits of complex devices obtained by a novel technique based on constitutive sub circuits and an Particle Swarm Optimization. In particular the robustness of the obtained circuits is evaluated by a sensitivity analysis, which leads to the identification of the range of variation of its frequency response, since different runs of the global extraction procedure lead to slightly different equivalent circuits (yet topologically coincident). The analysis of the numerical results give an insight on the robustness of as single case and at the same time attest the efficiency of the extraction technique

Interference of Spread-Spectrum Modulated Disturbances on Digital Communication Channels

In this paper, the effects of random spread spectrum (SS) electromagnetic interference (EMI) on digital communications are addressed. For this purpose, the influence of EMI on a communication channel is described in the framework of information theory in terms of an equivalent channel capacity loss, which is analytically predicted and validated by experimental results. The EMI-induced channel capacity loss for non-modulated and SS-modulated interference generated by a switching-mode DC-DC power converter are then evaluated for different EMI and channel characteristics so that to compare different scenarios of practical interest

FPGA-Based Relaxation D/A Converters With Parasitics-Induced Error Suppression and Digital Self-Calibration

In this paper, the implementation on a Field Programmable Gate Array (FPGA) of Relaxation Digital to Analog Converters (ReDACs), which take advantage of the impulse response of a first-order RC network to generate and combine binary weighted voltages, is addressed. For this purpose, the dominant ReDAC nonlinearity limitation related to the parasitics of the RC network is analyzed and a simple and robust technique for its effective suppression is proposed. Moreover, a ReDAC foreground digital calibration strategy suitable to FPGA implementation is introduced to tune the clock frequency of the converter, as requested for ReDAC operation. The novel error suppression technique and calibration strategy are finally implemented on a 13-bit, 514,S/s prototype (ReDAC1) and on a 11-bit, 10.5,kS/s prototype (ReDAC2), which are experimentally characterized under static and dynamic conditions. Measured results on ReDAC1 (ReDAC2) reveal 1.68,LSB (1.53,LSB) maximum INL, 1.54,LSB (1.0,LSB) maximum DNL, 76.4,dB (67.9,dB) THD, 79.7,dB (71.4,dB) SFDR and 71.3,dB (63.3,dB) SNDR, corresponding to 11.6 (10.2) effective bits (ENOB)