ACTIVE FILTERS SYNTHESIS TO SIMULATED LADDER NETWORKS AND FEEDBACK CIRCUITS

Abstract

An important feature in the design of passive and active filters networks is the method of the analysis employed. The purpose of this work is to synthesis two active low pass filters, the first is doubly terminated sixth order RLC passive ladder network and the second is multiple feedback network. The analyzing of the ladder network is achieved using graph-theoretic approach and the simulation is realized via MATLAB software tool version 8.1.0.604 (R2010a) using Butterworth values for a corner frequency of ω_c=1 MHz. A confirmation of results is achieved by nodal analysis and numerical analysis using Newton-Raphson method, respectively. The synthesized complete circuit requires 14 operational amplifiers and uses voltage subtractors and non-inverting integrators as building blocks with capacitors and inductors values evaluated from choosing R=1 "kΩ" as an arbitrary value. For the second network, an RC passive circuit is used, the feedback and feedforward transfer function are obtained using the transformed T-network. The elements values of an active network are computed by considering a corner frequency of ω_c=10 kHz.