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low-pass-filtering
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A new low power 2-2 cascaded Sigma-Delta modulator with the reduced number of op-amps for GSM transceiver applications
, Article 2003 10th IEEE International Conference on Electronics, Circuits and Systems, ICECS2003, Sharjah, 14 December 2003 through 17 December 2003 ; Volume 1 , 2003 , Pages 268-271 ; 0780381637 (ISBN); 9780780381636 (ISBN) ; Vahidfar, M. B ; Aslanzadeh, H ; Mehrmanesh, S ; Sharif University of Technology
2003
Abstract
A new single-bit cascaded 2-2 σ/δ (Sigma-Delta) modulator with only two op-amps, instead of four ones in conventional modulators, to decrease the static power consumption and area, is designed for GSM transceiver applications. The circuit consists of two new single op-amp, second-order, and low-pass loop filters to achieve a fourth-order quantization noise shaping. The modulator shows 84dB DR (Dynamic Range) for GSM signal bandwidth, while consuming 2.3mW from a 2.5V supply voltage. © 2003 IEEE
Synthesis and analysis of sigma-delta modulators employing continuous-time filters
, Article Analog Integrated Circuits and Signal Processing, Dordrecht, Netherlands ; Volume 23, Issue 2 , 2000 , Pages 141-152 ; 09251030 (ISSN) ; Keramat, M ; Kielbasa, R ; Sharif University of Technology
Kluwer Academic Publishers
2000
Abstract
A methodology for analysis and synthesis of lowpass sigma-delta (∑Δ) converters is presented in this paper. This method permits the synthesis of ∑Δ modulators employing continuous-time filters from discrete-time topologies. The analysis method is based on the discretization of a continuous-time model and using a discrete simulator, which is more efficient than an analog simulator. In our analysis approach, the influence of the sample and hold block and non-idealities of the feedback DAC can be systematically modeled by discrete-time systems. Finally, a realistic design of a second-order ∑Δ modulator with a compensation of the non-ideal behavior of the DAC is given. Moreover, simulation...
Design and Simulation of Integrated Bio-Impedance Driver and Sensor Circuits
, M.Sc. Thesis Sharif University of Technology ; Sharifkhani, Mohammad (Supervisor)
Abstract
Cardiovascular diseases stand as leading contributors to human mortality and disability, with heart muscle diseases, particularly acute and chronic failures, prevalent among them. While various diagnostic methods exist, an accurate, non-invasive, portable, easily accessible, and minimally disruptive approach for monitoring, requiring no frequent clinic visits, takes precedence. Early diagnosis and continuous fluid status monitoring through bioimpedance measurements of chest size are crucial in mitigating the mortality associated with these diseases. Utilizing bioimpedance as a non-invasive signal, this system facilitates ongoing vital parameter monitoring, treatment strategy optimization,...
Design and Implenentation of a Bandpass Delta-sigma Modulator Using High-Q N-path Filter
, M.Sc. Thesis Sharif University of Technology ; Atarodi,Mojtaba (Supervisor) ; Sharifkhani, Mohammad (Co-Supervisor)
Abstract
Delta-Sigma Analog-to-Digital converters have been positioned themselves as robust reliable converters so far. The magic Of extracting high resolutions from low bit ADC has made them popular between designers. Previously, the noise-shaping magic was used in high-resolution applications such as high-quality audio signal converters. However, as the technology scales and proceeds, these converters are approaching RF applications, too. Power and OSR trade-off limits this progress. To increase OSR in bandpass delta-sigma modulators, more power should be consumed to increase the quality factor of loop filters. In this thesis, a systematic approach has been utilized. An n-path filter is employed...
A high-order compact finite-difference lattice Boltzmann method for simulation of steady and unsteady incompressible flows
, Article International Journal for Numerical Methods in Fluids ; Vol. 75, Issue. 10 , 2014 , Pages 713-746 ; ISSN: 02712091 ; Ezzatneshan, E ; Sharif University of Technology
Abstract
A high-order compact finite-difference lattice Boltzmann method (CFDLBM) is proposed and applied to accurately compute steady and unsteady incompressible flows. Herein, the spatial derivatives in the lattice Boltzmann equation are discretized by using the fourth-order compact FD scheme, and the temporal term is discretized with the fourth-order Runge-Kutta scheme to provide an accurate and efficient incompressible flow solver. A high-order spectral-type low-pass compact filter is used to stabilize the numerical solution. An iterative initialization procedure is presented and applied to generate consistent initial conditions for the simulation of unsteady flows. A sensitivity study is also...
An ant-based rate allocation algorithm for media streaming in peer to peer networks: Extension to multiple sessions and dynamic networks
, Article Journal of Network and Computer Applications ; Volume 34, Issue 1 , 2011 , Pages 327-340 ; 10848045 (ISSN) ; Salavati, A. H ; Pakravan, M. R ; Sharif University of Technology
Abstract
In this paper, we introduce a novel algorithm for rate allocation in media streaming P2P networks where multimedia contents are distributed among network members and streamed toward any requesting peer. The proposed algorithm is based on ant-colony optimization. It is capable of handling network dynamism, which is an inherent property of unstructured P2P networks. Another advantage of our algorithm is its ability to get over uncertainties in network state information, particularly the rate of supplying peers that could happen due to lack of accurate measurements. In addition, the suggested method does not rely on any information about the topology of the network. We have investigated both...
Comparison of uniform and random sampling for speech and music signals
, Article 2017 12th International Conference on Sampling Theory and Applications, SampTA 2017, 3 July 2017 through 7 July 2017 ; 2017 , Pages 552-555 ; 9781538615652 (ISBN) ; Shahsavari, S ; Marvasti, F ; Sharif University of Technology
Abstract
In this paper, we will provide a comparison between uniform and random sampling for speech and music signals. There are various sampling and recovery methods for audio signals. Here, we only investigate uniform and random schemes for sampling and basic low-pass filtering and iterative method with adaptive thresholding for recovery. The simulation results indicate that uniform sampling with cubic spline interpolation outperforms other sampling and recovery methods. © 2017 IEEE
Ultra-low power frequency-shift keying demodulator based on injection-locking ring oscillator without using phase locked loop for wireless body area networks
, Article Electronics Letters ; Volume 53, Issue 16 , 2017 , Pages 1148-1150 ; 00135194 (ISSN) ; Safarian, A ; Sharif University of Technology
Abstract
An ultra-low power frequency-shift keying (FSK) demodulator based on injection-locking ring oscillator for wireless body area networks is presented. The proposed system uses the power-efficient injectionlocking ring oscillator (ILRO) to replace the LC oscillator which occupies much more area on chip with higher power consumption. In addition, through the ILRO, the frequency modulated input signal is converted to a full swing rectangular signal, which can be directly demodulated by a chain of down-conversion passive mixers, lowpass filters and a comparator. Power efficiency and simplicity of the proposed structure eliminate conventional FSK demodulator based on power-hungry phase locked...
A tunable-Q 4-path bandpass filter with Gm-C second-order baseband impedances
, Article 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 244-248 ; 9781509059638 (ISBN) ; Babamir, S. M ; Behmanesh, B ; Atarodi, S. M ; Sharif University of Technology
Abstract
An active switched-capacitor 4-path bandpass filter suitable for multi-standard applications in ultra-high frequency (UHF) band with different channel bandwidths is designed and simulated in 0.18 μm CMOS technology. The baseband impedance of the filter is implemented as a second-order Gm-C low-pass filter which can be used to tune the channel bandwidth as well as the quality factor (Q) of the RF filter. The center frequency of the filter can be tuned from 100 MHz up to 1.5 GHz by changing the clock frequency applied to the filter while its bandwidth can be tuned by tuning impedance parameters in any center frequency. To do so, the baseband impedance utilizes a frequency dependent negative...