Matos, C, Ortigueira MD.
2010.
Fractional Filters: An Optimization Approach. Emerging Trends in Technological Innovation. 314:361–366.
AbstractThe design and optimization of fractional filters is considered in this paper. Some of the classic filter architectures are presented and their performances relatively to an ideal amplitude spectrum evaluated. The fractional filters are designed using the differential evolution optimization algorithm for computing their parameters. To evaluate the performances of all the filters the quadratic error between the computed amplitude is calculated against an ideal (goal) response. The fractional filters have a better behavior, both in the pass and reject-band.
Evans, G, Goes J, Steiger-Garção A, Ortigueira MD, Paulino N, Sousa-Lopes J.
2003.
Low-voltage low-power CMOS analogue circuits for Gaussian and uniform noise generation, May. IEEE International Symposium on Circuits and Systems. :145–148.
AbstractA CMOS analogue circuit for Gaussian noise generation as well as a novel circuit for transforming Gaussian noise into uniform noise, both designed for operating with a supply voltage of 1.5V, are presented. Both circuits are optimized for a 0.35 {\ensuremathμ}m standard CMOS technology using an equation-based design methodology based on genetic algorithms. Electrical simulations demonstrate that high noise amplitudes together with reasonable bandwidths can be achieved with relatively low power dissipation. Potential applications include self-calibration and on-chip self-testing of video-rate analogue-to-digital converters.
Nascimento, B, Batista A, Alves LB, Ortigueira M, Rato R.
2010.
MicroECG: An Integrated Platform for the Cardiac Arrythmia Detection and Characterization. Emerging Trends in Technological Innovation. 314:367–373.
AbstractA software tool for the analysis of the High-Resolution Electrocardiogram (HR-ECG) for Arrhythmia detection is introduced. New algorithms based on Wavelet analysis are presented and compared with the classic Simson protocol over the P and QRS segments of the Electrocardiogram (EEG). A novel procedure based on a two step wavelet analysis and synthesis is performed in order to obtain a frequency description of the P, T or QRS segments. This frequency ?signature? is useful for the detection of otherwise asymptomatic Arrhythmia patients. The tool has been developed in Matlab, and deployed for a standalone C application.
Ricardo, CN, Inácio JA, Gerald JA, Ortigueira MD.
2003.
New BCH-Derived Sequences for CDMA Systems. 46th IEEE - Midwest Symposium on Circuits and Systems. :1255–1258.
AbstractNew BCH-derived PN-EB (pseudo-noise even balanced) sequences suitable to be used in CDMA systems are presented in this paper. It is assumed a new definition for processing gain, which better accounts for the system performance regarding the narrow band noise rejection, and it is shown how to obtain high processing gain values, namely, by using zero mean spreading signals in channels with selective noise. The new sequences have low autocorrelation levels, exist in large numbers and can provide higher processing gain with selective noise.
] 