jasem jamali Articles List

List of Articles jasem jamali

Open Access Article
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1 - Design of Novel Low-Power Single-Loop Sigma-Delta Modulator by Reduction of Amplifiers in the Loop-Filter for Speech Recognition Applications
Sahar Doolabi Mehdi Taghizadeh Mohammad Hossein Fatehi Jasem Jamali
20.1001.1.23223871.1403.15.57.7.6

In this paper, a novel general architecture for single-loop Sigma-Delta Modulator is presented by combination low-distortion and noise-coupled techniques for high-resolution low-power applications. The low-distortion technique in the proposed architecture makes its sign More

In this paper, a novel general architecture for single-loop Sigma-Delta Modulator is presented by combination low-distortion and noise-coupled techniques for high-resolution low-power applications. The low-distortion technique in the proposed architecture makes its signal transfer function equal to one. In addition, the noise-coupled technique increases the order of quantization noise shaping at the modulator output. The purpose of using these techniques in design of the architecture is to increase the order of the modulator without needing to additional operational amplifiers during its circuit implementation to finally achieve a low-power modulator compared to similar ones. To reduce the required amplifiers, a second order infinite impulse response (IIR) filter was used instead of an integrator in the modulator loop. To evaluate the performance of the proposed structure, its implementation and simulation for speech recognition application, i.e., digital hearing aids, were performed in 180nm CMOS (complementary metal-oxide semiconductor) technology. For a third-order structure with a sampling rate of 64 and an input sine signal of -6dBFS and a sampling frequency of 2.56MHz, the signal to noise and distortion (SNDR) is 81.9dB and the dynamic range (DR) is 88dB. The power consumption of the modulator is 126.9 μW and its bandwidth is 20 KHz. The results of circuit and system level simulations prove its performance. Manuscript profile
Open Access Article
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2 - Dual-Polarized MED Antenna by Using Metallic Plates for Mobile Communication Applications
Farshad Ghaedi Jasem Jamali Mehdi Taghizadeh
20.1001.1.23223871.1401.13.52.9.4

A new design of a dual-polarized base-station antenna with a wideband, low profile and high performance is introduced in this work for the LTE700/GSM850/GSM900 applications. The proposed base-station antenna in this study is comprised of four single-polarized magneto-el More

A new design of a dual-polarized base-station antenna with a wideband, low profile and high performance is introduced in this work for the LTE700/GSM850/GSM900 applications. The proposed base-station antenna in this study is comprised of four single-polarized magneto-electric dipoles (MEDs) antenna are positioned with a square arrangement to produce ±45° slant polarization. Each antenna is involved with an electrical dipole, a Γ-shaped feed structure, a magnetical dipole, a metallic resonator, and a cylindrical-shaped reflector. Three metallic portions with a slit produce the electrical dipole. Adjusting the dimensions of these segments and resonator plate improve the antenna impedance bandwidth. Also, the cylindrical-shaped reflector increases the antenna gain and has a significant rule to stabilize the antenna radiation pattern. The measurements exhibit that this antenna achieves an expanded frequency bandwidth of 38.1% (686.2-1008.8 MHz) for |S11| < –15 dB, realized peak gain of 11.45 dBi, low cross-polarization, and half-power beamwidths (HPBWs) of approximately 60.4°, 64.7°, and 66.8° at frequencies of 700 MHz, 8500 MHZ, and 900 MHz respectively. Results approve that the above-mentioned antenna is applicable for mobile cellular networks systems. Manuscript profile

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List of Articles jasem jamali