International Journal of Circuit Theory and Applications

Cover image for Vol. 42 Issue 1

January 2014

Volume 42, Issue 1

Pages 1–109

  1. Research Articles

    1. Top of page
    2. Research Articles
    1. Frequency–amplitude relations for cross-coupled voltage-controlled oscillator (pages 28–42)

      Abdollah Eskandarian

      Version of Record online: 30 JUL 2012 | DOI: 10.1002/cta.1831

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      Closed form expressions are derived for frequency of oscillation as a function of amplitude, for positive and negative control bias voltages. Theory of nonlinear ordinary differential equations is utilized to show that the capacitance–voltage nonlinearity is the main cause of frequency shift with amplitude. A closed form expression is derived for dependence of frequency on small amplitudes. This relation is then verified using the concept of effective capacitance. The effective capacitance approach is also used to extend the analysis to large voltage swings. Dependence of frequency on tuner control voltage is calculated for both bias polarities.

    2. A high-order curvature-corrected CMOS bandgap voltage reference with constant current technique (pages 43–52)

      Junfeng Geng, Yiqiang Zhao and Hongliang Zhao

      Version of Record online: 1 AUG 2012 | DOI: 10.1002/cta.1836

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      The novel BGR comprises a bipolar transistor Q1 with an approximately proportional to the absolute temperature collector operating current and a bipolar transistor Q2 with a constant collector operating current. The ratio of the collector current densities in the bipolar transistors Q1 and Q2 varies with temperature, and the difference between the base–emitter voltages of the above two bipolar transistors includes a residual voltage which approximately compensates for the nonlinear temperature dependency of VBE.

    3. Theoretical and experimental analysis of a simple PWM-1 controlled interrupted electric circuit (pages 53–64)

      Hiroyuki Asahara and Takuji Kousaka

      Version of Record online: 17 SEP 2012 | DOI: 10.1002/cta.1837

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      We analyze the bifurcation phenomena in a simple PWM-1 controlled interrupted electric circuit. It will be clarified that the period-doubling bifurcation and the border-collision bifurcation occur in the circuit dynamics and they affect the region in which the periodic solution exist. The mathematical results are verified through the experiment.

    4. Gate-level body biasing technique for high-speed sub-threshold CMOS logic gates (pages 65–70)

      P. Corsonello, M. Lanuzza and S. Perri

      Version of Record online: 1 AUG 2012 | DOI: 10.1002/cta.1838

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      An efficient technique for designing high-performance logic circuits operating in sub-threshold region is proposed. A simple gate-level body biasing circuit is exploited to change dynamically the threshold voltage of transistors on the basis of the gate status. Such an auxiliary circuit prepares the logic gate for fast switching while maintaining energy efficiency.

      If 200 aJ is the target total energy per operation consumption, a two input NAND (NOR) gate designed as described here shows a delay reduction between 20% (16%) and 40% (48%), with respect to previously proposed sub-threshold approaches.

    5. Ladder tuning-block partitioned filters for simplified tuning (pages 71–95)

      Drazen Jurisic and George S. Moschytz

      Version of Record online: 14 AUG 2012 | DOI: 10.1002/cta.1839

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      In this paper we present a procedure for the design of low-sensitivity, active-RC filters that permits efficient functional tuning during the manufacturing process. Filters with finite zeros, such as elliptic (Chebyshev-Cauer) low-pass filters are primarily considered, although the method can be applied to the design of other filters, e.g. allpole filters, as well. We show how to partition a given ladder filter into two parts. The first is a ladder filter of reduced order compared to the original; the second is a second- or third-order active-RC filter section, the ‘tuning block’, which, alone is used to tune the overall filter. The ladder, the components of which are fixed, provides most of the selectivity, while the cascaded tuning block determines the band-edge characteristics, and can be tuned relatively easily. A detailed design procedure for the filter partitioning is given. By obtaining a doubly terminated ladder filter, which is cascaded with a tuning block, both the inherent low sensitivity of the ladder, and the tunability of the tuning block, are maintained. A Monte Carlo analysis of the partitioned filter demonstrates that the low sensitivity with respect to component tolerances, achievable by maintaining a doubly terminated ladder structure for the larger partitioned part of the filter, is preserved.

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