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Design of Voltage-Mode, Trans-Admittance-Mode, Trans-Impedance-Mode and Current-Mode Biquad Filters Employing Plus Type Current Feedback Amplifiers
N.A. Shah and M. F. Rather

In this paper two filter configurations one operating in voltage-mode (VM) and the other in trans-impedance-mode(TIM) with each employing three non-inverting current feedback amplifiers (CFAs) along with seven passive components are presented. The VM filter with three inputs and three outputs enjoy the features of: realizing all the generic filtering functions by proper choice of inputs with three responses simultaneously, ideal for cascading due to its inputs at high impedances and outputs at low impedances, and realizing trans-admittancemode (TAM) filtering functions from the same topology. The TIM circuit with a single input and three outputs has the features of: realizing three filtering functions simultaneously, ideal for cascadibility because of having input at zero impedance and outputs at low impedances, and implementing current-mode(CM) filtering responses from the same configuration. These filtering topologies besides having low active and passive sensitivities show that their filtering parameters cut-off frequency (wo), bandwidth(wo/Q), quality factor(Q) and gain(Ho) permit either orthogonal or independent adjustment. The current and voltage tracking errors of the active devices have been included and to confirm the theoretical analysis, experimental and PSPICE simulation results are shown.

Keywords: Voltage-mode, mixed-mode, current-mode filters, current feedback amplifier.

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