New resistorless and electronically tunable realization of dual-output VM all-pass filter using VDIBA
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CitationHerencsar, N., Minaei, S., Koton, J., Yüce, E., & Vrba, K. (2013). New resistorless and electronically tunable realization of dual-output VM all-pass filter using VDIBA. Analog Integrated Circuits and Signal Processing, 74(1). 141-154. https://dx.doi.org/10.1007/s10470-012-9936-2
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 non-inverting outputs at the same configuration simultaneously. The pole frequency of the filter can be electronically controlled by means of bias current of the internal trans-conductance. 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 second-order 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 mu m 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.