Zied Sakka

A reliable approach to distinguish between transient with and without HFOs using TQWT and MCA.

Recent studies have reported that discrete high frequency oscillations (HFOs) in the range of 80-500Hz may serve as promising biomarkers of the seizure focus in humans. Visual scoring of HFOs is tiring, time consuming, highly subjective and requires a great deal of mental concentration. Due to the recent explosion of HFOs research, development of a robust automated detector is expected to play a vital role in studying HFOs and their relationship to epileptogenesis. Therefore, a handful of automated detectors have been introduced in the literature over the past few years. In fact, all the proposed methods have been associated with high false-positive rates, which essentially arising from filtered sharp transients like spikes, sharp waves and artifacts. In order to specifically minimize false positive rates and improve the specificity of HFOs detection, we proposed a new approach, which is a combination of tunable Q-factor wavelet transform (TQWT), morphological component analysis (MCA) and complex Morlet wavelet (CMW). The main findings of this study can be summarized as follows: The proposed method results in a sensitivity of 96.77%, a specificity of 85.00% and a false discovery rate (FDR) of 07.41%. Compared to this, the classical CMW method applied directly on the signals without pre-processing by TQWT-MCA achieves a sensitivity of 98.71%, a specificity of 18.75%, and an FDR of 29.95%. The proposed method may be considered highly accurate to distinguish between transients with and without HFOs. Consequently, it is remarkably reliable and robust for the detection of HFOs.

A 4GHz temperature compensated CMOS ring oscillator for impulse radio UWB

This paper presents a voltage controlled ring oscillator (VCO) with a simpler temperature compensation circuit to produce a stable 4 GHz oscillation frequency. The proposed temperature compensation circuit is able to achieve a 89.25 % reduction in the variation of the center frequency of the uncompensated VCO and 108 ppm/°C temperature stability. Simulations using TSMC 0.18 µm CMOS technology show a low phase noise of a −74.55 dBc/Hz at 1 MHz offset from the carrier and a total power consumption of 11.06 mA. Therefore, the proposed oscillator system is suitable for the impulse radio ultra wide band (IR-UWB) wireless communication system.

Design and Optimization of Differential Ring Oscillator for IR-UWB Applications in 0.18 μm CMOS Technology

This study presents a two-stage ring voltage-controlled oscillator (VCO) for use in impulse-radio ultra-wideband (IR-UWB) applications. A systematic and efficient graphical optimization method was employed to find the optimal dimensions of the VCO which give a best performance. A good agreement was observed between the desired specifications and simulation results with regard to the optimum component size of the VCO circuit. The operation range of the VCO was extended to cover an ultra-wide tuning range of 176.6%. The phase noise was −107.1dBc/Hz at 10MHz offset frequency from a carrier frequency of 4GHz. The power consumption of VCO was 7.41mW from a 1.8V supply voltage. A large tuning range, low power, and appropriate phase noise were obtained with the optimum components size obtained through the optimization method.

A Low-Power Ring Oscillator with Temperature Compensation for IR-UWB Applications

This paper presents a 4GHz low-power ring oscillator with supply and temperature compensation for use in impulse-radio ultra-wideband (IR-UWB) applications. Simulations using TSMC 0.18μm CMOS techn...