Y.P. Tsividis

Columbia University, New York City, NY, United States

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Publications (42)42.5 Total impact

  • L. Toth, Y.P. Tsividis
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    ABSTRACT: The concept of traditional chopper-stabilized amplifiers is extended to general linear dynamical and certain types of nonlinear circuits. Simulation results are given to confirm the theory.
    IEEE Transactions on Circuits and Systems I Fundamental Theory and Applications 09/2003;
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    N. Krishnapura, Y.P. Tsividis
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    ABSTRACT: A technique that enables the variation of bias currents in a filter without causing disturbances at the output is presented. Thus, the bias current can be kept at the minimum value necessary for the total input signal being processed, reducing the noise and power consumption. To demonstrate this approach, a dynamically biased log-domain filter has been designed in a 0.25-μm BiCMOS technology. The chip occupies 0.52 mm<sup>2</sup>. In its quiescent condition, the filter consumes 575 μW and has an output noise of 4.4 nA rms. Signal-to-noise ratio greater than 50 dB over 3 decades of input and total harmonic distortion less than 1% for inputs less than 2.5 mA peak are achieved. The bias can be varied to minimize noise and power consumption without disturbing the output
    IEEE Journal of Solid-State Circuits 01/2002; · 3.06 Impact Factor
  • L. Toth, G. Palaskas, Y.P. Tsividis
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    ABSTRACT: Two novel methods are described for syllabic companding in signal processors. These methods make state variable updating unnecessary, for piecewise constant input and output gains. Measurements and simulations are used as confirmation of the validity of the proposed techniques
    IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing 01/2002;
  • Eric A. Vittoz, Yannis P. Tsividis
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    ABSTRACT: In analog circuits, a fundamental trade-off exists between power consumption, signal-to-noise ratio and available bandwidth, as expressed by equation (10.1). The absolute minimum value2 of factor K that quantifies this trade-off is 8. However, independently of any process limitation, this minimum may be larger, depending on the function that is considered and on the approach used for its implementation: signal swing smaller than the supply voltage, several poles and/or high-Q poles in active filters, current or voltage amplification. A severe increase of K may be caused by the need to achieve linearity in spite of the nonlinear transfer characteristics of active devices. In practice, K is further increased by process-dependent limitations including parasitic capacitors, additional noise sources with respect to fundamental thermal or shot noise, mismatch of components and charge injection by switches. Lowering the supply voltage below a few volts usually causes an increase of K, but it may help to reduce it in cases where the signal swing is limited. The dynamic range of a circuit, which is often considered similar to the maximum value of its signal-to-noise ratio, can be extended much beyond it by resorting to companding techniques.
    12/2001: pages 283-313;
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    ABSTRACT: A general theory for companding log domain filters is proposed which combines not only exponential mappings, but also a new translational mapping approach which guarantees suitable operating conditions in any log domain filter. The filter equations resulting from the use of the theory ultimately contain translinear terms which are known to be realizable using translinear techniques. A discussion of the design of the companding filters, regarding the economical use of translinear loops and the convenient selection of system parameters, is offered which leads to first- and second-order circuit designs. Finally, the noise performance of an example design is investigated using a carefully crafted large-signal simulation technique, showing clearly the advantage of the companding filter approach
    IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing 05/2001;
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    ABSTRACT: This paper presents a systematic noise analysis method for externally linear filters, suitable for hand calculations. As an illustrative example, a log-domain filter is analyzed. Applying this method to an abstract topology, bounds for signal-to-noise ratio are derived for a class of instantaneous companding filters, when total capacitance or total power are limited.
    Analog Integrated Circuits and Signal Processing 01/2001; 28(1):63-72. · 0.55 Impact Factor
  • L. Toth, G. Efthivoulidis, Y.P. Tsividis
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    ABSTRACT: Noise analysis in externally linear time-invariant systems is complicated by the facts that noise sources may not be stationary and the relationships between the noise sources and the output are generally nonlinear. In this paper, we present a general noise analysis method which can be used to speed up repetitive noise calculations for a given system, and, most importantly, for theoretical investigations of its noise behavior, possibly leading to low-noise design techniques. A current mode syllabic companding and two log-domain filters are analyzed as illustrative examples
    IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing 01/2001;
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    S. Pavan, Y.P. Tsividis, K. Nagaraj
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    ABSTRACT: We present design considerations for programmable high-frequency continuous-time filters implemented in standard digital CMOS processes. To reduce area, accumulation MOS capacitors are used as integrating elements. The filter design problem is examined from the viewpoint of programmability. To allow frequency scalability without deterioration of noise performance and of the frequency response shape, we employ a technique called “constant-capacitance scaling,” which assures that even parasitic capacitances remain invariant when transconductors are switched in and out of the filter. This technique is applied to the design of a programmable fourth order Butterworth continuous-time filter with a bandwidth programmable from 60 to 350 MHz implemented in a 0.25-μm digital CMOS process. The filter has a dynamic range of 54 dB, dissipates 70 mW from a 3.3-V supply, and occupies an area of 0.15 mm<sup>2</sup>
    IEEE Journal of Solid-State Circuits 05/2000; · 3.06 Impact Factor
  • Dandan Li, Y.P. Tsividis
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    ABSTRACT: A novel loss-control loop for use in voltage-controlled oscillator indirect tuning systems of radio-frequency continuous-time filters is presented. In contrast to conventional schemes, this loop can achieve robust amplitude regulation
    IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing 04/2000;
  • G. Efthivoulidis, L. Toth, Y.P. Tsividis
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    ABSTRACT: In this paper, we summarize a noise analysis method which is valid for any externally linear circuit, and is suitable for both automated and hand calculations assuming white noise input. A second order log-domain filter example illustrates the method
    Circuits and Systems, 2000. 42nd Midwest Symposium on; 02/1999
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    L. Toth, Y.P. Tsividis, N. Krishnapura
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    ABSTRACT: Certain issues in the analysis of the effects of noise and interference in instantaneously companding signal processors is discussed. Important differences from the analysis and effects encountered in conventional signal processors are pointed out, and are illustrated by deriving analytical results for deterministic small interference and stationary random noise in a first-order instantaneously companding filter. The theoretical calculations are successfully compared to experimental results
    IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing 10/1998;
  • G. Efthivoulidis, L. Toth, Y.P. Tsividis
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    ABSTRACT: Noise due to resistors and op amps in active RC and MOSFET-C filters is considered. Bounds for the signal-to-resistive noise ratio and signal-to-op amp noise ratio in state-space filters are given
    IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing 10/1998;
  • Y.P. Tsividis
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    ABSTRACT: The concepts behind externally linear, internally nonlinear integrators are reviewed, and the contest in which such integrators can find use in signal processing is discussed. Several examples of specific cases are offered, including log-domain, exponential state space, square root domain, piecewise-linear, and nonlinear capacitance circuits. Several issues requiring caution are discussed
    IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing 10/1998;
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    S. Pavan, Y.P. Tsividis
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    ABSTRACT: We present a completely analytical solution to a filter-comparator oscillator system, and verify it by macromodel simulations and experiment. We discuss the applications of this kind of oscillator in a vector-locked loop system for continuous time filter tuning. We also apply our solution to the operation of a resonant switched mode inverter
    IEEE Transactions on Circuits and Systems I Fundamental Theory and Applications 06/1998;
  • G. Efthivoulidis, L. Toth, Y.P. Tsividis
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    ABSTRACT: Noise in Gm-C filters is discussed. Topology-independent bounds for the signal-to-noise ratio (SNR) are derived, assuming the total power dissipation or the total capacitance are specified. Expressions for certain products of noise with frequently used quantities are derived, and are shown to be invariant under certain actions, which are sometimes taken in order to improve the SNR. Finally, specification-dependent bounds for SNR are derived
    IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing 04/1998;
  • D.R. Frey, Y.P. Tsividis
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    ABSTRACT: It is shown that syllabic companding in a log domain filter can be accomplished by varying the bias currents, thus eliminating the need for separate compressor and expander blocks. The advantages of the proposed technique are discussed
    Electronics Letters 09/1997; · 1.04 Impact Factor
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    ABSTRACT: The electrical properties of a six-terminal MOSFET are studied and a strong-inversion model is derived. Due to its special structure, the six-terminal MOSFET can be operated as a highly-linear, electronically-tunable resistor. This is managed by applying proper voltages at the terminals of the structure, achieving channel uniformity independent of applied signals. Measurements on fabricated test devices yield distortion levels of -90 dB for 1 V<sub>p-p</sub> signals
    IEEE Journal of Solid-State Circuits 02/1997; · 3.06 Impact Factor
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    S. Pipilos, Y.P. Tsividis, J. Fenk, Y. Papananos
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    ABSTRACT: A second-order active bandpass filter using integrated inductors was implemented in Si bipolar technology. The filter uses special techniques to make the quality factor and the center frequency tunable. For a nominal center frequency of 1.8 GHz and a quality factor of 35, the filter has 1 dB compression dynamic range of 40 dB, and draws 8.7 mA from a 2.8 V supply
    IEEE Journal of Solid-State Circuits 11/1996; · 3.06 Impact Factor
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    ABSTRACT: Resistive noise in active RC and MOSFET-C filters is examined. The effects of impedance and frequency scaling are shown. The relationship between sensitivity and noise is considered. A bound for the product of resistive power dissipation and noise power spectral density is derived. Topology-independent and transfer function-independent bounds for the dynamic range, in filters with power dissipation constraint, are developed
    IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing 01/1996;
  • Y.P. Tsividis
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    ABSTRACT: The state of the art of continuous-time filter design is reviewed. Several techniques are discussed and compared in terms of performance and implementation feasibility in different fabrication technologies. This review does not aim at historical completeness, but rather emphasizes techniques that have proven their worth in commercial applications. Brief mention is also made of experimental work which, in the opinion of the author, shows promise for the future
    IEEE Journal of Solid-State Circuits 04/1994; · 3.06 Impact Factor

Publication Stats

1k Citations
42.50 Total Impact Points

Institutions

  • 1986–2003
    • Columbia University
      • Department of Electrical Engineering
      New York City, NY, United States
  • 2001
    • Massachusetts Institute of Technology
      Cambridge, Massachusetts, United States
  • 1992–1999
    • National Technical University of Athens
      • • School of Electrical and Computer Engineering
      • • Division of Computer Science
      Athens, Attiki, Greece
  • 1997
    • Lehigh University
      • Department of Electrical and Computer Engineering
      Bethlehem, PA, United States
  • 1993–1996
    • Budapest University of Technology and Economics
      Budapeŝto, Budapest, Hungary
  • 1989
    • AT&T Labs
      Austin, Texas, United States