A Single Resistor Tunable Grounded Capacitor Dual-Input Differentiator

Abstract

A new current feedback amplifier (CFA) based dual-input differentiator (DID) design with grounded capacitor is presented; its time constant ( τ o ) is independently tunable by a single resistor. The proposed circuit yields a true DID function with ideal CFA devices. Analysis with nonideal devices having parasitic capacitance ( C p ) shows extremely low but finite phase error ( θ e ); suitable design θ e could be minimized significantly. The design is practically active-insensitive relative to port mismatch errors ( ε ) of the active element. An allpass phase shifter circuit implementation is derived with slight modification of the differentiator. Satisfactory experimental results had been verified on typical wave processing and phase-selective filter design applications.