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)

A modified version of voltage differencing current conveyor (VDCC) and its performance in detail is presented in this paper. Modified VDCC, so-called z-copy controlled gain voltage differencing current conveyor (ZC-CG-VDCC), offers interesting features from adjustability point of view. The active element allows independent electronic control of three adjustable parameters: intrinsic resistance of current input terminal, transconductance and current gain of the output stage which is not possible in case of conventional VDCC. The characteristics of proposed CMOS implementation designed using TSMC LO EPI 0.18 m technology process parameters are shown and discussed. Simple application in reconfigurable reconnection-less first-order voltage-mode multifunctional filter is shown and verified by SPICE simulations and experimentally. The filter tuning and change of the transfer function type is allowed by the controllable parameters of the ZC-CG-VDCC.

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.

Several behavioral models of current active elements for experimental purposes are introduced in this paper. These models are based on commercially available devices. They are suitable for experimental tests of current-and mixed-mode filters, oscillators, and other circuits (employing current-mode active elements) frequently used in analog signal processing without necessity of onchip fabrication of proper active element. Several methods of electronic control of intrinsic resistance in the proposed behavioral models are discussed. All predictions and theoretical assumptions are supported by simulations and experiments. This contribution helps to find a cheaper and more effective way to preliminary laboratory tests without expensive on-chip fabrication of special active elements.

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