In this paper, a new active element called voltage differencing inverting buffered amplifier (VDIBA) is presented. Using single VDIBA and a capacitor, a new resistorless voltage-mode (VM) first-order all-pass filter (APF) is proposed, which provides both inverting and noninverting outputs at the same configuration simultaneously. The pole frequency of the filter can be electronically controlled by means of bias current of the internal transconductance. No component-matching conditions are required and it has low sensitivity. In addition, the parasitic and loading effects are also investigated. By connecting two newly introduced APFs in open loop a novel secondorder APF is proposed. As another application, the proposed VM APF is connected in cascade to a lossy integrator in a closed loop to design a four-phase quadrature oscillator. The theoretical results are verified by SPICE simulations using TSMC 0.18 lm level-7 CMOS process parameters with ±0.9 V supply voltages. Moreover, the behavior of the proposed VM APF was also experimentally measured using commercially available integrated circuit OPA860 by Texas Instruments.Keywords Analog signal processing Á All-pass filter Á Electronically tunable circuit Á Four-phase quadrature oscillator Á Loading effect Á Resistorless filter Á Voltage-mode Á Voltage differencing inverting buffered amplifier (VDIBA)

Due to the absence of commercially available fractional-order capacitors and inductors, their implementation can be performed using fractional-order di®erentiators and integrators, respectively, combined with a voltage-to-current conversion stage. The transfer function of fractional-order di®erentiators and integrators can be approximated through the utilization of appropriate integer-order transfer functions. In order to achieve that, the Continued Fraction Expansion as well as the Oustaloup's approximations can be utilized. The accuracy, in terms of magnitude and phase response, of transfer functions of di®erentiators/integrators derived through the employment of the aforementioned approximations, is very important factor for achieving high performance approximation of the fractional-order elements. A comparative study of the accuracy o®ered by the Continued Fraction Expansion and the Oustaloup's approximation is performed in this paper. As a next step, the corresponding implementations of the emulators of the fractional-order elements, derived using fundamental active cells such as operational ampli¯ers, operational transconductance ampli¯ers, current conveyors, and current feedback operational ampli¯ers realized in commercially available discrete-component IC form,

Abstract:In this paper, new minimal configuration precision fullwave rectifier is presented. The structure employs one current and one voltage conveyor and only two diodes. It enables to process both low-voltage and low-current signals. Compared to the op amp based circuit, the proposed circuit is able to rectify signals up to 500 kHz and beyond with no or small distortion. Experimental measurements are performed that show the feasibility of the new precision full-wave rectifier. Keywords: analog processing circuits, current conveyor, instrumentation and measurements, precision full-wave rectifier, voltage conveyor Classification: Electronic instrumentation and control References[1] U. Tietze, C. Schenk, and E. Gramm, "Electronic Circuits-Handbook for Design and Application," Springer, 2008. [2] C. Toumazou and F. J. Lidgey, "Fast current-mode precision rectifier,"Electron. Wireless Wolrd, vol. 93, no. 1621Wolrd, vol. 93, no. , pp. 1115Wolrd, vol. 93, no. -1118Wolrd, vol. 93, no. , 1987 S. J. G. Gift and B. Maundy, "Versatile Precision Full-Wave Rectifiers for Intrumentation and Measurements," IEEE Trans. Instrum. Meas., vol. 56, no. 5, pp. 1703-1710, 2007 C. Toumazou, F. J. Lidgey, and S. Chattong, "High frequency current conveyor precision full-wave rectifier," Electron. Lett., vol. 30, no. 10, pp. 745-746, 1994. [5] A. A. Khan, M. A. El-Ela, and M. A. Al-Turaigi, "Current-mode precision rectification," Int. J. Electron., vol. 79, no. 6, pp. 853-859, 1995. [6] B. Wilson and V. Mannama, "Current-mode rectifier with improved precision," Electron. Lett., vol. 31, no. 4, pp. 247-248, 1995. [7] D. Stiurca, "Truly temperature independent current conveyor precision rectifier," Electron. Lett., vol. 31, no. 16, pp. 1302Lett., vol. 31, no. 16, pp. -1303Lett., vol. 31, no. 16, pp. , 1995 S. Minaei and E. Yuce, "A new full-wave rectifier employing single dual-X current conveyor," Int. J. Electron., vol. 95, no. 8, pp. 777-784, 2008. [9] S. J. G. Gift, "A High-performance full-wave rectifier circuit," Int. J. Electron., vol. 87, no. 8, pp. 925-930, 2000 Electron. Lett., vol. 17, no. 3, pp. 129-130, 1981. [19] T. Dostal and J. Pospisil, "Hybrid models of 3-port immittance convertors and current and voltage conveyors," Electron. Lett., vol. 18, no. 20, pp. 887-888, 1982. Microelectronics Journal, vol. 30, no. 2, pp. 157-160, 1999. [22] J. Koton, K. Vrba, and N. Herencsar, "Tuneable filter using voltage conveyors and current active elements," Int. J. Electron., vol. 96, no. 8, pp. 787-794, 2009. [23] N. Herencsar, J. Koton, and K. Vrba, "A new electronically tunable voltage-mode active-C phase shifter using UVC and OTA," IEICE Electron. Express, vol. 6, no. 17, pp. 1212Express, vol. 6, no. 17, pp. -1218Express, vol. 6, no. 17, pp. , 2009 IJCSNS, vol. 6, no. 3A, pp. 57-65, 2006. [27] J. Jerabek and K. Vrba, "SIMO type low-input and high-output impedance current-mode universal filter employing three universal current conveyors," AEU -Int.

The paper presents a new realization of active RC sinusoidal oscillator with electronically tunable condition and frequency of oscillation. As compared to the class of three resistors, two capacitors (3R-2C) based canonic oscillators, the proposed circuit here uses only two resistors and two capacitors as the passive components and still provides non-interactive tuning laws for the condition of oscillation (CO) and the frequency of oscillation (FO). The proposed circuit employs new bipolar programmable current amplifier (PCA) as the active building block and is capable of simultaneously providing two explicit quadrature current outputs. SPICE simulation results have been included to verify the workability of the circuit as an oscillator and the tuning range of the FO.

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