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  Subjects -> COMPUTER SCIENCE (Total: 2002 journals)
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COMPUTER SCIENCE (1160 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 872 Journals sorted alphabetically
3D Printing and Additive Manufacturing     Full-text available via subscription   (Followers: 13)
Abakós     Open Access   (Followers: 3)
Academy of Information and Management Sciences Journal     Full-text available via subscription   (Followers: 72)
ACM Computing Surveys     Hybrid Journal   (Followers: 22)
ACM Journal on Computing and Cultural Heritage     Hybrid Journal   (Followers: 9)
ACM Journal on Emerging Technologies in Computing Systems     Hybrid Journal   (Followers: 13)
ACM Transactions on Accessible Computing (TACCESS)     Hybrid Journal   (Followers: 3)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 16)
ACM Transactions on Applied Perception (TAP)     Hybrid Journal   (Followers: 6)
ACM Transactions on Architecture and Code Optimization (TACO)     Hybrid Journal   (Followers: 9)
ACM Transactions on Autonomous and Adaptive Systems (TAAS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Computation Theory (TOCT)     Hybrid Journal   (Followers: 11)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 4)
ACM Transactions on Computer Systems (TOCS)     Hybrid Journal   (Followers: 18)
ACM Transactions on Computer-Human Interaction     Hybrid Journal   (Followers: 13)
ACM Transactions on Computing Education (TOCE)     Hybrid Journal   (Followers: 4)
ACM Transactions on Design Automation of Electronic Systems (TODAES)     Hybrid Journal   (Followers: 1)
ACM Transactions on Economics and Computation     Hybrid Journal  
ACM Transactions on Embedded Computing Systems (TECS)     Hybrid Journal   (Followers: 4)
ACM Transactions on Information Systems (TOIS)     Hybrid Journal   (Followers: 20)
ACM Transactions on Intelligent Systems and Technology (TIST)     Hybrid Journal   (Followers: 8)
ACM Transactions on Interactive Intelligent Systems (TiiS)     Hybrid Journal   (Followers: 3)
ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP)     Hybrid Journal   (Followers: 10)
ACM Transactions on Reconfigurable Technology and Systems (TRETS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Sensor Networks (TOSN)     Hybrid Journal   (Followers: 8)
ACM Transactions on Speech and Language Processing (TSLP)     Hybrid Journal   (Followers: 11)
ACM Transactions on Storage     Hybrid Journal  
ACS Applied Materials & Interfaces     Full-text available via subscription   (Followers: 22)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Ad Hoc Networks     Hybrid Journal   (Followers: 11)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Advanced Engineering Materials     Hybrid Journal   (Followers: 26)
Advanced Science Letters     Full-text available via subscription   (Followers: 7)
Advances in Adaptive Data Analysis     Hybrid Journal   (Followers: 8)
Advances in Artificial Intelligence     Open Access   (Followers: 16)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 15)
Advances in Computer Science : an International Journal     Open Access   (Followers: 13)
Advances in Computing     Open Access   (Followers: 2)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 52)
Advances in Engineering Software     Hybrid Journal   (Followers: 25)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Human-Computer Interaction     Open Access   (Followers: 20)
Advances in Materials Sciences     Open Access   (Followers: 16)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 37)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Advances in Technology Innovation     Open Access   (Followers: 2)
AEU - International Journal of Electronics and Communications     Hybrid Journal   (Followers: 8)
African Journal of Information and Communication     Open Access   (Followers: 7)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 4)
Air, Soil & Water Research     Open Access   (Followers: 8)
AIS Transactions on Human-Computer Interaction     Open Access   (Followers: 6)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1)
Algorithms     Open Access   (Followers: 11)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 4)
American Journal of Computational Mathematics     Open Access   (Followers: 4)
American Journal of Information Systems     Open Access   (Followers: 7)
American Journal of Sensor Technology     Open Access   (Followers: 4)
Anais da Academia Brasileira de Ciências     Open Access   (Followers: 2)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 7)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Animation Practice, Process & Production     Hybrid Journal   (Followers: 5)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Data Science     Hybrid Journal   (Followers: 9)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 6)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Software Engineering     Hybrid Journal   (Followers: 12)
Annual Reviews in Control     Hybrid Journal   (Followers: 6)
Anuario Americanista Europeo     Open Access  
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applied and Computational Harmonic Analysis     Full-text available via subscription   (Followers: 2)
Applied Artificial Intelligence: An International Journal     Hybrid Journal   (Followers: 14)
Applied Categorical Structures     Hybrid Journal   (Followers: 2)
Applied Clinical Informatics     Hybrid Journal   (Followers: 2)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Computer Systems     Open Access   (Followers: 1)
Applied Informatics     Open Access  
Applied Mathematics and Computation     Hybrid Journal   (Followers: 33)
Applied Medical Informatics     Open Access   (Followers: 11)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Soft Computing     Hybrid Journal   (Followers: 16)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Architectural Theory Review     Hybrid Journal   (Followers: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 5)
Archive of Numerical Software     Open Access  
Archives and Museum Informatics     Hybrid Journal   (Followers: 128)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Artifact     Hybrid Journal   (Followers: 2)
Artificial Life     Hybrid Journal   (Followers: 6)
Asia Pacific Journal on Computational Engineering     Open Access  
Asia-Pacific Journal of Information Technology and Multimedia     Open Access   (Followers: 1)
Asian Journal of Computer Science and Information Technology     Open Access  
Asian Journal of Control     Hybrid Journal  
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
Australian Educational Computing     Open Access  
Automatic Control and Computer Sciences     Hybrid Journal   (Followers: 3)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Automatica     Hybrid Journal   (Followers: 9)
Automation in Construction     Hybrid Journal   (Followers: 6)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Basin Research     Hybrid Journal   (Followers: 5)
Behaviour & Information Technology     Hybrid Journal   (Followers: 52)
Bioinformatics     Hybrid Journal   (Followers: 302)
Biomedical Engineering     Hybrid Journal   (Followers: 16)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 32)
Briefings in Bioinformatics     Hybrid Journal   (Followers: 44)
British Journal of Educational Technology     Hybrid Journal   (Followers: 123)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
c't Magazin fuer Computertechnik     Full-text available via subscription   (Followers: 2)
CALCOLO     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Journal of Electrical and Computer Engineering     Full-text available via subscription   (Followers: 14)
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal  
Cell Communication and Signaling     Open Access   (Followers: 1)
Central European Journal of Computer Science     Hybrid Journal   (Followers: 5)
CERN IdeaSquare Journal of Experimental Innovation     Open Access  
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
ChemSusChem     Hybrid Journal   (Followers: 7)
China Communications     Full-text available via subscription   (Followers: 7)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
CIN Computers Informatics Nursing     Full-text available via subscription   (Followers: 12)
Circuits and Systems     Open Access   (Followers: 16)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
CLEI Electronic Journal     Open Access  
Clin-Alert     Hybrid Journal   (Followers: 1)
Cluster Computing     Hybrid Journal   (Followers: 1)
Cognitive Computation     Hybrid Journal   (Followers: 4)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Communication Methods and Measures     Hybrid Journal   (Followers: 11)
Communication Theory     Hybrid Journal   (Followers: 20)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Algebra     Hybrid Journal   (Followers: 3)
Communications in Partial Differential Equations     Hybrid Journal   (Followers: 3)
Communications of the ACM     Full-text available via subscription   (Followers: 53)
Communications of the Association for Information Systems     Open Access   (Followers: 18)
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering     Hybrid Journal   (Followers: 3)
Complex & Intelligent Systems     Open Access  
Complex Adaptive Systems Modeling     Open Access  
Complex Analysis and Operator Theory     Hybrid Journal   (Followers: 2)
Complexity     Hybrid Journal   (Followers: 6)
Complexus     Full-text available via subscription  
Composite Materials Series     Full-text available via subscription   (Followers: 9)
Computación y Sistemas     Open Access  
Computation     Open Access  
Computational and Applied Mathematics     Hybrid Journal   (Followers: 2)
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2)
Computational and Mathematical Organization Theory     Hybrid Journal   (Followers: 2)
Computational and Structural Biotechnology Journal     Open Access   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Astrophysics and Cosmology     Open Access   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 12)
Computational Chemistry     Open Access   (Followers: 2)
Computational Cognitive Science     Open Access   (Followers: 2)
Computational Complexity     Hybrid Journal   (Followers: 4)
Computational Condensed Matter     Open Access  
Computational Ecology and Software     Open Access   (Followers: 9)
Computational Economics     Hybrid Journal   (Followers: 9)
Computational Geosciences     Hybrid Journal   (Followers: 14)
Computational Linguistics     Open Access   (Followers: 23)
Computational Management Science     Hybrid Journal  
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 4)
Computational Methods and Function Theory     Hybrid Journal  
Computational Molecular Bioscience     Open Access   (Followers: 2)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Particle Mechanics     Hybrid Journal   (Followers: 1)
Computational Research     Open Access   (Followers: 1)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computational Science and Techniques     Open Access  
Computational Statistics     Hybrid Journal   (Followers: 13)
Computational Statistics & Data Analysis     Hybrid Journal   (Followers: 31)
Computer     Full-text available via subscription   (Followers: 85)
Computer Aided Surgery     Hybrid Journal   (Followers: 3)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Communications     Hybrid Journal   (Followers: 10)
Computer Engineering and Applications Journal     Open Access   (Followers: 5)
Computer Journal     Hybrid Journal   (Followers: 7)
Computer Methods in Applied Mechanics and Engineering     Hybrid Journal   (Followers: 22)
Computer Methods in Biomechanics and Biomedical Engineering     Hybrid Journal   (Followers: 10)
Computer Methods in the Geosciences     Full-text available via subscription   (Followers: 1)
Computer Music Journal     Hybrid Journal   (Followers: 16)
Computer Physics Communications     Hybrid Journal   (Followers: 6)
Computer Science - Research and Development     Hybrid Journal   (Followers: 7)
Computer Science and Engineering     Open Access   (Followers: 17)
Computer Science and Information Technology     Open Access   (Followers: 11)
Computer Science Education     Hybrid Journal   (Followers: 12)
Computer Science Journal     Open Access   (Followers: 20)
Computer Science Master Research     Open Access   (Followers: 10)
Computer Science Review     Hybrid Journal   (Followers: 10)

        1 2 3 4 5 6 | Last

Journal Cover Analog Integrated Circuits and Signal Processing
  [SJR: 0.21]   [H-I: 37]   [7 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1573-1979 - ISSN (Online) 0925-1030
   Published by Springer-Verlag Homepage  [2352 journals]
  • A power-efficient 14.8-GHz CMOS programmable frequency divider with
           quadrature outputs in 40-nm CMOS process
    • Authors: Sen Huang; Shengxi Diao; Fujiang Lin
      Pages: 189 - 196
      Abstract: Abstract This paper presents a power-efficient CMOS frequency divider (FD) with wide-band programmable division ratio and quadrature outputs for high-speed data transmission applications. The proposed FD consists of a power-efficient programmable divider (PD), a complementary volt-age-to-time converter based duty-cycle correction circuit, and a compact quadrature divider (QD). In the chain of PD, a sense-amplifier based dynamic flip-flop is proposed for 2/3 divider cell to achieve high-speed operation with significantly reduced power consumption. In addition, a simple but effective QD based on two pseudo-differential voltage-controlled tri-state inverters, is beneficial for generating precise quadrature output signals. Measurement results in 40-nm CMOS process show that the proposed FD achieves a wide division range from 16 to 254 and operates up to 14.8 GHz while consuming the power of 540.6 μW at 1.1-V supply, and occupying the active area of 0.00267 mm2 (114.6 μm × 23.3 μm).
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1037-9
      Issue No: Vol. 93, No. 2 (2017)
       
  • A highly efficient class-EF 2 power amplifier in GaAs pHEMT technology
    • Authors: A. R. Dehqan; Siroos Toofan; Ali Medi
      Pages: 197 - 203
      Abstract: Abstract This paper presents a highly efficient class-EF2 power amplifier in GaAs pHEMT technology with high output power. Drain swing voltage of class-E power amplifier (PA) imposes a restriction on its output power. In this work, using a combination of class-E and F relaxes this limitation which may help in increasing DC supply voltage. Higher DC supply voltage of class-EF2 PA leads to increased output power and efficiency, as output power is proportional to supply voltage. In addition, higher supply voltage permits PA to work under lower current which can cause to reduce power dissipation. Proposed class-EF2 PA is implemented in a single recess AlGaAs–InGaAs pHEMT technology with 0.25-µm gate length; power added efficiency of 52% at 31 dBm output power is achieved at 1.8 GHz.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1038-8
      Issue No: Vol. 93, No. 2 (2017)
       
  • A 0.1–1.1 GHz inductorless differential LNA with double g m -boosting
           and positive feedback
    • Authors: Xu Yan; Cen Chen; Lu Yang; Jili Zhang; Fujiang Lin
      Pages: 205 - 215
      Abstract: Abstract A 0.1–1.1 GHz wideband low-noise amplifier (LNA) is proposed in this paper. The LNA is a fully differential common-gate structure. Large equivalent transconductance \((g_m)\) is realized by active \(g_m\) -boost and capacitive cross-coupling. By introducing a positive feedback path, the circuit increases design freedom. It alleviates the tradeoff between input matching, gain and noise performance. The proposed LNA avoids the use of on-chip inductors to save area and cost. A prototype is implemented in standard TSMC 180-nm CMOS technology. From the measurement, the proposed LNA shows a 19 dB voltage gain with a 1 GHz 3-dB bandwidth. The minimum noise figure (NF) is 3.1 dB. The LNA achieves a return loss greater than 10 dB across the entire band and the third-order input-referred intercept (IIP3) is better than \(-\,2.9\)  dBm. The core consumes 3.8 mW from 1-V supply occupying an area of 0.03  \(\hbox {mm}^2\) .
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1043-y
      Issue No: Vol. 93, No. 2 (2017)
       
  • Design and analysis of a low-noise saw-less receiver front-end resistant
           to strong out-of-band blocker
    • Authors: Amin Mohammadpour; Abdolreza Nabavi
      Pages: 217 - 235
      Abstract: Abstract Design and analysis of a SAW-less front-end resistant to strong out-of-band blocker is presented which utilizes a main-path containing an LNA along with a 12.5% mixer and a baseband amplifier. Also, it employs an auxiliary-path using a 12.5% mixer and a baseband amplifier. Multiple N-path filtering technique is employed to improve the NF and gain of the front-end in the presence of strong out-of-band blocker. The linearity of LNA, enhanced by series resistors in the LNA inputs, is analyzed by Volterra series analysis. Using noise cancellation technique on this structure relaxes the concern of series resistor noise contribution. Furthermore, new analyses are given for N-path-switching clock non-idealities, considering overlap and its effect on input matching. Analysis and simulation results, using 0.18 µm CMOS technology, show about 6 and 5 dB improvement in LNA IIP3 and front-end NF, respectively, when series resistor is added to the LNA and the auxiliary-path is ON.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1035-y
      Issue No: Vol. 93, No. 2 (2017)
       
  • A segmentation layout guarding technique to mitigate parasitic capacitance
           of integrated resistors
    • Authors: Zhijun Zhou; Paul Warr
      Pages: 237 - 243
      Abstract: Abstract Within integrated circuit design, parasitic capacitance associated with the realisation of a resistor can limit circuit performance for certain applications, such as the analogue-to-digital converter. In this paper, a segmentation guarding layout technique is introduced that offers the circumvention of the parasitic capacitance of integrated resistors. The segmentation guarding technique is demonstrated on both diffusion and polysilicon integrated resistors.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-0982-7
      Issue No: Vol. 93, No. 2 (2017)
       
  • A 700 MHz laser radar receiver realized in 0.18 μm HV-CMOS
    • Authors: Mikko Hintikka; Juha Kostamovaara
      Pages: 245 - 256
      Abstract: Abstract This study presents a CMOS receiver chip realized in 0.18 µm High-Voltage CMOS (HV-CMOS) technology and intended for high precision pulsed time-of-flight laser range finding utilizing high-energy sub-ns laser pulses. The IC chip includes a trans-impedance preamplifier, a post-amplifier and a timing comparator. Timing discrimination is based on leading edge detection and the trailing edge is also discriminated for measuring the width of the pulse. The transimpedance of the channel is 25 kΩ, the uncompensated walk error is 470 ps in the dynamic range of 1:21,000 and the input referred equivalent noise current 450 nA (rms).
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1041-0
      Issue No: Vol. 93, No. 2 (2017)
       
  • Low power ring oscillator for IoT applications
    • Authors: Rajendra Nayak; Iman Kianpoor; Pydi Ganga Bahubalindruni
      Pages: 257 - 263
      Abstract: Abstract This paper proposes a low power ring oscillator by combining current starving technique with negative skewed delay approach. This design has shown an improvement of more than 50% in the power delay product compared to the state of the art techniques. Circuit simulations are carried out in standard 65 nm technology. The proposed circuit has shown a robust performance against temperature and voltage variation within 10%. Therefore this circuit can find potential applications in IoT devices and RFID tags operating from 10 MHz to 1 GHz.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1015-2
      Issue No: Vol. 93, No. 2 (2017)
       
  • A new hybrid TDC based on GRO-pseudo delay architecture with fractional
           code and wide time range detection for divider-less ADPLL
    • Authors: Mongia Mhiri; Sehmi Saad; Aymen Ben Hammadi; Kamel Besbes
      Pages: 265 - 275
      Abstract: Abstract This paper presents a novel Time-to-digital converter (TDC) for All Digital Phase Locked Loop (ADPLL) able to reach high linearity and wide input range with normalized fractional output code. The topology is based on startable Pseudo differential delay cells. It arbiters in a gated ring oscillator (GRO) format in manner to extend measurement time interval. A normalization unit is developed to free calibrate output and to measure phase errors for divider-less ADPLL applications. The proposed TDC is designed in 90 nm CMOS process. Simulation results show that the TDC achieves a large detectable conversion range that extends between 0.285 and 10 ns. The attained time resolution is 9.4 ps, which corresponds to half the delay time of an inverter. The TDC is self-calibrating with estimated accuracy better than 0.28%. The structure consumes 6.6 mA current from a 1.0 V voltage supply, when operating at a clock frequency of 13 MSPS. The estimated differential nonlinearity and integral nonlinearity are ±0.48 LSB and ±0.6 LSB respectively. Compared to previously reported TDC, this implementation achieves a competitive FoMP without requiring complicate calibration.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1032-1
      Issue No: Vol. 93, No. 2 (2017)
       
  • An open loop compensation technique for reducing supply sensitivity of CML
           ring oscillator
    • Authors: Ziqian Wang; Xuefei Bai; Shengxi Diao; Fujiang Lin
      Pages: 277 - 285
      Abstract: Abstract The causes of supply induced noise are investigated and a circuit technique that reduces the supply sensitivity of CML ring oscillator is presented. This technique applies a current bias circuit with negative supply sensitivity to compensate the intrinsic positive sensitivity of VCO and alleviate the impact of supply voltage fluctuation. A prototype chip is fabricated in a 180 nm CMOS process to prove its rejection of supply noise.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1039-7
      Issue No: Vol. 93, No. 2 (2017)
       
  • Analysis and design of low-voltage low-power high-speed double tail
           current dynamic latch comparator
    • Authors: Vijay Savani; N. M. Devashrayee
      Pages: 287 - 298
      Abstract: Abstract The demanding need of ultra-high speed, area efficient and power optimized analog-to-digital converter is forcing towards the exploration and usage of the dynamic regenerative comparator to minimize the power, area and maximize the speed. In this paper, detailed analysis of the delay for the various dynamic latch based comparators is presented and analytical expressions are derived. With the help of analytical expressions, the designer can obtain insight view of the different parameters, which are the contributors of the delay in the dynamic comparator. Based on the findings, various tradeoffs can be explored. Based on the literature and presented analysis, a new dynamic latch based comparator is proposed. The basic double tail dynamic latch based comparator and shared charge logic are modified for low-power and high-speed with the reduced power supply in the proposed comparator. With the modified structure of double tail latch comparator and adding the shared charge logic, the regeneration delay is reduced, at the same time, power consumption is also reduced. Simulation results in 90 nm CMOS technology confirm the claimed reductions. The simulation is carried out using 90 nm technology with a supply voltage of 1 V, at 1 GHz of frequency resulting into the delay of 50.9 ps while consuming 31.80 μW of power.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1040-1
      Issue No: Vol. 93, No. 2 (2017)
       
  • Analog circuit sizing using local biasing
    • Authors: Srdjan Dragomira Djordjevic
      Pages: 299 - 308
      Abstract: Abstract The analog circuit design approach based on local biasing is shown to be very attractive as it removes the nonlinearity in the biasing procedure. Based on this design approach, we offer a new technique for the sizing of analog integrated circuits. The proposed technique is based on the relations that exist between linear elements of a cut-set or a loop when the voltages and currents in the remaining elements are held fixed. These relations enable the designer to fix a circuit variable (biasing current or voltage of a transistor) in exchange for a set of interrelated element values that can be independently changed. The proposed procedure allows us to directly change the element values or the DC parameter values for the active loads without being concerned about the DC biasing. Therefore, the circuit designer is able to manage tradeoffs in the design by comparing multiple solutions that meet the desired criteria. Moreover, multiple circuit simulations are not necessary in the case when any of the calculated element values is not realistic or workable.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1017-0
      Issue No: Vol. 93, No. 2 (2017)
       
  • Linear in dB, sub 0.2 dB gain-step CMOS programmable gain amplifier
           for ultrasound applications
    • Authors: Yarallah Koolivand; Omid Shoaei; Shahin Jafarabadi-Ashtiani
      Pages: 309 - 318
      Abstract: Abstract In this paper a new approach for controlling the gain of a programmable gain amplifier (PGA) using an eight-bit digital word has been proposed. Eight stages of R–2R ladder attenuators have been employed for attenuating the input signal. The output of the ladder network feeds the nine gm stages as a part of the PGA. Making use of three MSB bits of the control word, at each instance just the two successive gm stages are active whose tail currents are precisely determined to set the PGA linear gain in dB. A current bank composed of 32 current sources has been used for driving the tail currents of the active gm stages. The current sources that bias the active gm stages are controlled by the five LSB bits of the digital control word. Thanks to the proposed technique, the values of the current sources are determined so that the gain of the circuit is based on a ratio-metric parameter making the circuit less sensitive to process variations. For verification of the proposed idea, a differential PGA is design in a 0.18 µm 1.8 V CMOS technology. The gain of the designed circuit changes from 20.8 to −27.4 dB in 256 steps linearly in dB so that the maximum gain error respect to its ideal value is less than 0.03 dB in different corner cases. At the maximum gain, the bandwidth and the input referred noise voltage of the PGA are 150 MHz and 3.5 nv/√Hz, respectively, while the overall circuit draws 6 mA from a 1.8 V power supply.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1016-1
      Issue No: Vol. 93, No. 2 (2017)
       
  • Bio-cellular processes modeling on silicon substrate: receptor–ligand
           binding and Michaelis Menten reaction
    • Authors: Maria Waqas; Muhammad Khurram; S. M. Rezaul Hasan
      Pages: 329 - 340
      Abstract: Abstract There has been a growing interest and motivation in analog electronic circuit modeling of bio-cellular networks, which forms the basis of cellular functions of all living organisms. The complexity and size of such networks has made this task arduous, while opening up new opportunities as well. A number of modeling techniques, from mathematical models to computer simulations, have been used in this domain to aid the interpretation of such complex and sophisticated networks. This research article focuses on modeling of bio-cellular structures and processes on silicon substrate using transistors in analog domain. MOS transistor analogies for some very commonly found bio-cellular reactions namely receptor–ligand kinetics and Michaelis Menten kinetics have been presented, which are based on previously established ordinary differential equation representation models of these bio-cellular processes. It has been shown mathematically and through simulations that a number of bio-chemical entities in the kinetic processes map naturally to some electronic entities, and exploiting these similarities can drastically reduce the size of the corresponding silicon mimetics. The suggested circuits use lesser number of transistors than the existing approaches in this domain, while producing the same behavior satisfactorily. This can to some extent ease the development of larger networks with more complex interactions, hence mitigating the intricacy involved in cellular processes when viewed as a complete system and can contribute positively to multiple disciplines like genetics, bio-informatics, medical sciences, and even computer science and engineering.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1044-x
      Issue No: Vol. 93, No. 2 (2017)
       
  • Enhancement of noise-suppressed speech by spectral processing implemented
           in a digital signal processor
    • Authors: Hajer Rahali; Zied Hajaiej
      Pages: 341 - 350
      Abstract: Abstract This paper presents a noisy suppressed speech enhancement method by combining the basic spectral subtraction technique and spectral processing in the frequency domain to provide better noise suppression as well as better enhancement in the speech regions. In contrast to several previous approaches we do not try to achieve a complete removal of the noise, but instead our goal is to preserve a pre-defined amount of the original noise in the processed signal. This is accomplished by exploiting the masking properties of the human auditory system. The proposed algorithm is named PM “Proposed Method” which simulates properties of the human auditory system and applies it to the speech recognition system to enhance its robustness. The performance of the speech enhancement algorithm using the proposed masking model was compared with three other speech enhancement methods over 4 different noise types and five SNRs. The performances of the proposed approach are objectively and subjectively compared to the conventional approaches to highlight the aforementioned improvement. In this paper we discuss the design and development of a digital signal processor (DSP) implementation to achieve real-time performance of our filter. The target processor is a Texas Instruments TMS320C6713 floating point DSP.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1042-z
      Issue No: Vol. 93, No. 2 (2017)
       
  • A novel full-wave rectifier/sinusoidal frequency doubler topology based on
           CFOAs
    • Authors: Erkan Yuce; Shahram Minaei; Muhammed A. Ibrahim
      Pages: 351 - 362
      Abstract: Abstract A novel topology for realizing voltage-mode (VM) full-wave rectifier/sinusoidal frequency doubler based on current feedback operational amplifiers (CFOAs) and n-channel metal-oxide semiconductor (NMOS) transistors is proposed in this study. The proposed full-wave rectifier structure employs two CFOAs and three enhancement-mode NMOS transistors. With a slight modification, the sinusoidal frequency doubler circuit can be adopted from the full-wave rectifier circuit by replacing a grounded resistor instead of one of the NMOS transistors. Both of the proposed circuits enjoy low output and high input impedance properties which make them convenient for cascading easily with other VM circuits without needing any extra buffer circuits. No passive component matching conditions are needed. The proposed circuits are simulated by using SPICE program to verify the theoretical analysis.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1033-0
      Issue No: Vol. 93, No. 2 (2017)
       
  • Memristor-based approximate matrix multiplier
    • Authors: Mohsen Nourazar; Vahid Rashtchi; Ali Azarpeyvand; Farshad Merrikh-Bayat
      Pages: 363 - 373
      Abstract: Abstract The parallel structure of matrix multipliers makes them fascinating candidates to benefit from memristors’ high density architecture. This paper first explains a memristor-based analog vector–matrix multiplier suitable for approximate computing. According to the existence of fast and efficient converters, namely, DACs and ADCs, in the field of approximate computing and the programmability of memristors, the presented vector–matrix multiplier is combined with digital circuits which it leads to a matrix–matrix multiplier as an extension. In this work, opamps’ characteristics such as power and speed, distribution of matrix elements, and memristors’ faults have been considered and their effects on performance, accuracy, and efficiency of the proposed multiplier have been analyzed. Also, a new structure for handling negative numbers has been proposed. All the circuits have been simulated using “Ngspice mixed-signal circuit simulator” in C++ programming environment. The simulation results revealed that the multiplier’s analog core brought gains in terms of performance and energy when acceptable ranges of inaccuracies in results could be tolerated.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1029-9
      Issue No: Vol. 93, No. 2 (2017)
       
  • LSB split capacitor SAR ADC with 99.2% switching energy reduction
    • Authors: Behzad Ghanavati; Ebrahim Abiri; Mohammad Reza Salehi; Aida Keyhani; Arindam Sanyal
      Pages: 375 - 382
      Abstract: Abstract A highly energy efficient capacitor switching technique in a successive approximation register (SAR) analog to digital converter (ADC) for biomedical applications is presented. The proposed scheme based on new switching method, which combine the LSB split capacitive technique and monotonic method can reduce the average switching energy by 99.2% compared to the conventional SAR architecture. Besides reducing energy in each comparison cycle, the suggested method also achieves an 8× reduction in total capacitance used in the digital to analog converter over the conventional one with the same resolution. The proposed ADC can find application in biomedical engineering systems and other fields which low power consumption is needed.
      PubDate: 2017-11-01
      DOI: 10.1007/s10470-017-1046-8
      Issue No: Vol. 93, No. 2 (2017)
       
  • Contactless hand tremor detector based on an inductive sensor
    • Authors: W. Y. Shi; J.-C. Chiao
      Abstract: Abstract A contactless detector is presented for evaluating hand tremors caused by exercise-induced fatigue and early Parkinson’s disease. The device consists of a spiral coil, a microcontroller, and an inductive sensor circuitry. Theory shows that the resonant frequency of the circuitry increases when the distance between the hand and the spiral coil decreases, thus small variations of distance from tremor can be detected from the changes of resonant frequencies. A mechanical hand was built for experiments to simulate human hand tremors with repeatability at a fixed frequency. The magnitudes and frequencies of the tremors in the mechanical hand were quantitatively identified using the inductive sensor. Hence, feasibility and accuracy of the contactless hand tremor detector were determined. A triaxial accelerometer was used for comparison. By comparing spectral distributions and magnitudes of the tremors, the inductive sensor performed better than the accelerometer. The detector was applied to evaluate actual hand tremors of three subjects who had undergone exercise to induce tremors. The tremor waveform amplitudes of the subjects were quantitatively analyzed by the standard deviations method. The increased signal energies of exercise-induced tremor within 8–12 Hz were confirmed. Then, a subject with early Parkinson’s disease was evaluated by the proposed hand tremor detector. The tremor magnitudes and frequencies of the patient hand were quantitatively identified within in 4–7 Hz. Therefore, the new contactless hand tremor detector can be developed as a clinical instrument for monitoring the fatigue symptoms of post-exercise and diagnosing the early Parkinson’s disease.
      PubDate: 2017-10-11
      DOI: 10.1007/s10470-017-1055-7
       
  • Ultra low power beta multiplier-based current reference circuit
    • Authors: Shailesh Singh Chouhan; Kari Halonen
      Abstract: Abstract This work presents a current reference circuit fabricated in a standard 0.18 μm CMOS technology. The reference current is obtained by applying thermal compensation voltage in the conventional self-biased or beta multiplier-based current reference circuit. Eight prototypes of the proposed architecture were measured which have resulted into the mean reference current of 26.1 nA with the temperature coefficient of 202.1 ppm/°C. These measurements were performed in the temperature range of − 40 to + 85 °C. The circuit is capable of working over the supply voltage range of 1–2 V with the measured mean line sensitivity of 2.18%/V. The maximum measured power dissipation of the circuit is 104 nW at 2 V.
      PubDate: 2017-10-10
      DOI: 10.1007/s10470-017-1057-5
       
  • PSR enhancement techniques for output-capacitor-free LDO regulator design
    • Authors: Soyeon Joo; SoYoung Kim
      Abstract: Abstract In this paper, power-supply rejection (PSR) enhancement techniques for a output-capacitor-free low drop-out (LDO) regulator with an NMOS pass transistor are presented. For DC PSR and bandwidth enhancement, DC PSR compensation and capacitor cancelation circuits were developed on the basis of precisely derived PSR models of the conventional LDO regulator. The effectiveness of the PSR enhancement techniques were verified using analytic PSR models, SPICE simulation, and measurements. The fabricated LDO regulator using 0.18  \(\upmu\) m CMOS technology maintains PSR less than \(-74\,\hbox {dB}\) up to 10 MHz, while delivering the output current and voltage of 25 mA and 1.2 V, respectively.
      PubDate: 2017-10-04
      DOI: 10.1007/s10470-017-1045-9
       
 
 
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