The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Jose M. De La Rosa - One of the best experts on this subject based on the ideXlab platform.
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LC-Based Bandpass Continuous-Time Sigma-Delta Modulators With Widely Tunable Notch Frequency
IEEE Transactions on Circuits and Systems I: Regular Papers, 2014Co-Authors: Gerardo Molina-salgado, Alonso Morgado, Gordana Jovanovic Dolecek, Jose M. De La RosaAbstract:This paper analyses the use of bandpass continuous-time ΣΔ modulators with widely programmable Notch Frequency for the efficient digitization of radio-Frequency signals in the next generation of software-defined-radio mobile systems. The modulator architectures under study are based on a fourth-order loop filter - implemented with two LC-based resonators - and a finite-impulsive-response feedback loop in order to increase their flexibility and degrees of freedom. Several topologies are studied, considering three different cases for the embedded digital-to-analog converter, namely: return-to-zero, non-return-to-zero and raised-cosine waveform. In all cases, a Notch-aware synthesis methodology is presented, which takes into account the dependency of the loop-filter coefficients on the Notch Frequency and compensates for the dynamic range degradation due to the variation of the Notch. The synthesized modulators are compared in terms of their sensitivity to main circuit error mechanisms and the estimated power consumption over a Notch-Frequency tuning range of 0.1fs to 0.4fs. Time-domain behavioral and macromodel electrical simulations validate this approach, demonstrating the feasibility of the presented methodology and architectures for the efficient and robust digitization of radio-Frequency signals with a scalable resolution and programmable signal bandwidth.
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MWSCAS - Band-pass continuous-time ΣΔ modulators with widely tunable Notch Frequency for efficient RF-to-digital conversion
2013 IEEE 56th International Midwest Symposium on Circuits and Systems (MWSCAS), 2013Co-Authors: Gerardo Molina-salgado, Gordana Jovanovic-dolecek, Jose M. De La RosaAbstract:This paper presents a design methodology to synthesize band-pass continuous-time ΣΔ modulators with a widely programmable Notch Frequency for the efficient digitization of radio-Frequency signals in the next generation of software-defined-radio mobile systems. The presented modulator architectures are based on a fourth-order loop filter - implemented with two LC-based resonators - and a finite-impulsive-response feedback loop to increase their flexibility and degrees of freedom, considering three different cases for the digital-to-analog converter waveform, namely: a return-to-zero, a non-return-to-zero and a raised-cosine waveform. In all cases, the Notch Frequency can be reconfigured from 0.1fs to 0.4fs, while keeping the noise shaping performance, stability and low sensitivity to circuit-element tolerances. This feature can be combined with undersampling techniques to achieve an efficient and robust digitization of 0.5-to-5GHz signals with scalable resolution and programmable signal bandwidth1.
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ISCAS - Undersampling RF-to-digital CT ΣΔ modulator with tunable Notch Frequency and simplified raised-cosine FIR feedback DAC
2013 IEEE International Symposium on Circuits and Systems (ISCAS2013), 2013Co-Authors: Sohail Asghar, Rocío Del Río, Jose M. De La RosaAbstract:This paper presents a continuous-time fourth-order band-pass ΣΔ Modulator for digitizing radio-Frequency signals in software-defined-radio mobile systems. The modulator architecture is made up of two resonators and a 16-level quantizer in the feedforward path and a raised-cosine finite-impulsive-response feedback DAC. The latter is implemented with a reduced number of filter coefficients as compared to previous approaches, which allows to increase the Notch Frequency programmability from 0.0375/s to 0.25/s, while keeping stability and robustness to circuit-element tolerances. These features are combined with undersampling techniques to achieve an efficient and robust digitization of 0.455-to-5GHz signals with scalable 8-to-15bit effective resolution within 0.2-to-30MHz signal bandwidth, with a reconfigurable 1-to-4GHz sampling Frequency1.
R A Minasian - One of the best experts on this subject based on the ideXlab platform.
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ultrawide tunable microwave photonic Notch filter based on stimulated brillouin scattering
IEEE Photonics Technology Letters, 2012Co-Authors: Weiwei Zhang, R A MinasianAbstract:A new ultrawide tunable microwave photonic Notch filter that exhibits a very high resolution is presented. It is based on a stimulated Brillouin scattering technique, which processes the modulation sidebands generated by a dual-drive Mach-Zehnder modulator. Tuning is realized by changing the drive Frequency to an electro-optic intensity modulator. Experimental results demonstrate a high-resolution Notch filter with a 3-dB bandwidth of 82 MHz, a Notch depth of over 40 dB, a flat passband from near DC to 20 GHz with very low ripples, and a Notch Frequency that can be continuously tuned with shape invariance over an ultrawide Frequency range from 2 to 20 GHz.
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high resolution microwave photonic Notch filter with low noise and low group delay ripple performance
URSI General Assembly and Scientific Symposium, 2011Co-Authors: Erwin H W Chan, R A MinasianAbstract:A high-resolution microwave photonic Notch filter having a wide passband and a narrow Notch, is presented. It is based on a WDM multiple double-pass modulation approach using Bragg grating reflectors. The WDM laser powers are optimised to flatten the filter passband and to improve the filter group delay performance. The filter operates over a wide Frequency range, and the Notch Frequency is tunable. Experimental results demonstrate a microwave photonic Notch filter with a wide and flat passband, a narrow Notch at GHz Frequency and a high signal-to-noise ratio performance. Tunable coherence-free operation of the Notch filter is also shown.
K Martin - One of the best experts on this subject based on the ideXlab platform.
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an adaptive analog continuous time cmos biquadratic filter
IEEE Journal of Solid-state Circuits, 1991Co-Authors: T Kwan, K MartinAbstract:An adaptive analog continuous-time biquadratic filter is realized in a 2- mu m digital CMOS process for operation at 300 kHz. The biquad implements the Notch, bandpass and low-pass transfer functions. The only parameter adapted is the resonant Frequency of the biquad, which is identical to the Notch Frequency and the bandpass center Frequency. The update method is based on a least-means-square algorithm which adapts the Notch Frequency to minimize the power at the Notch filter output. The actual update is modified to reduce the circuit complexity to one biquad and one correlator. When the filter is tracking a sinusoid, this update generates a ripple-free gradient that decreases tracking error. Applications include phase-Frequency detectors, FM demodulators (linear and Frequency shift keying), clock extractors, and Frequency acquisition aids for phase-locked loops and Costas loops. Measured results from experimental prototypes are presented. Nonidealities of an all-analog implementation are discussed, along with suggestions to improve performance. >
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an adaptive analog continuous time cmos biquadratic filter
Custom Integrated Circuits Conference, 1991Co-Authors: T Kwan, K MartinAbstract:An adaptive analog continuous-time biquadratic filter is realized in a 2- mu m digital CMOS process for operation at 300 kHz. The biquad implements the Notch, bandpass, and lowpass transfer functions. The update method is based on a LMS algorithm which adapts the Notch Frequency to minimize the power at the Notch filter output. Applications include FM demodulators (linear and Frequency shift keying), clock extractors, and Frequency acquisition aids for phase-locked loops and Costas loops. Measured results from experimental prototypes are presented. >
Gerardo Molina-salgado - One of the best experts on this subject based on the ideXlab platform.
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LC-Based Bandpass Continuous-Time Sigma-Delta Modulators With Widely Tunable Notch Frequency
IEEE Transactions on Circuits and Systems I: Regular Papers, 2014Co-Authors: Gerardo Molina-salgado, Alonso Morgado, Gordana Jovanovic Dolecek, Jose M. De La RosaAbstract:This paper analyses the use of bandpass continuous-time ΣΔ modulators with widely programmable Notch Frequency for the efficient digitization of radio-Frequency signals in the next generation of software-defined-radio mobile systems. The modulator architectures under study are based on a fourth-order loop filter - implemented with two LC-based resonators - and a finite-impulsive-response feedback loop in order to increase their flexibility and degrees of freedom. Several topologies are studied, considering three different cases for the embedded digital-to-analog converter, namely: return-to-zero, non-return-to-zero and raised-cosine waveform. In all cases, a Notch-aware synthesis methodology is presented, which takes into account the dependency of the loop-filter coefficients on the Notch Frequency and compensates for the dynamic range degradation due to the variation of the Notch. The synthesized modulators are compared in terms of their sensitivity to main circuit error mechanisms and the estimated power consumption over a Notch-Frequency tuning range of 0.1fs to 0.4fs. Time-domain behavioral and macromodel electrical simulations validate this approach, demonstrating the feasibility of the presented methodology and architectures for the efficient and robust digitization of radio-Frequency signals with a scalable resolution and programmable signal bandwidth.
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MWSCAS - Band-pass continuous-time ΣΔ modulators with widely tunable Notch Frequency for efficient RF-to-digital conversion
2013 IEEE 56th International Midwest Symposium on Circuits and Systems (MWSCAS), 2013Co-Authors: Gerardo Molina-salgado, Gordana Jovanovic-dolecek, Jose M. De La RosaAbstract:This paper presents a design methodology to synthesize band-pass continuous-time ΣΔ modulators with a widely programmable Notch Frequency for the efficient digitization of radio-Frequency signals in the next generation of software-defined-radio mobile systems. The presented modulator architectures are based on a fourth-order loop filter - implemented with two LC-based resonators - and a finite-impulsive-response feedback loop to increase their flexibility and degrees of freedom, considering three different cases for the digital-to-analog converter waveform, namely: a return-to-zero, a non-return-to-zero and a raised-cosine waveform. In all cases, the Notch Frequency can be reconfigured from 0.1fs to 0.4fs, while keeping the noise shaping performance, stability and low sensitivity to circuit-element tolerances. This feature can be combined with undersampling techniques to achieve an efficient and robust digitization of 0.5-to-5GHz signals with scalable resolution and programmable signal bandwidth1.
Karu P. Esselle - One of the best experts on this subject based on the ideXlab platform.
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Prediction of the Notch Frequency of Slot Loaded Printed UWB Antennas
IEEE Transactions on Antennas and Propagation, 2007Co-Authors: T. Dissanayake, Karu P. EsselleAbstract:To prevent interference between ultrawideband (UWB) systems and existing wireless systems, creating Notches in the UWB radiated field spectrum has been proposed. This filtering effect can be achieved by integrating a slot resonator to a UWB antenna. However, in printed monopole or dipole type UWB antennas, the Notch Frequency of the embedded slot depends on substrate and slot parameters. In this paper, we present a method to calculate, very accurately and efficiently, the Notch Frequency of such antennas. This method is validated by comparing theoretical and experimental results for 19 different slot width, slot length and dielectric constant combinations. The average difference is about 2%. We also assess the filtering action of slots from two aspects: the mismatch loss at the input and the radiation level in the far field. The sensitivity of the Notch Frequency to antenna parameters is also investigated.
