Transresistance Multifunction Filter Using Current Feedback Amplifier

Active filters play important role in communication systems. They can be obtained and constructed by different methods. Recently, there is a tendency of designing current-mode circuits using unity-gain active elements such as, CFOAs, CCIIs, etc. instead of classical infinite gain operational amplifiers in active filter design. This paper presents transresistance multifunction filter realization using current-feedback operational amplifiers (CFOAs). A CFOA is similar to CCII structure except its output buffer. AD844 of AD is used as CFOA, so its unity gain buffer can be used as voltage monitoring. The need for such filters with different input and output variables rises in the application of A/D converter with current output. Such A/D converters follow by a reconstruction filter with current input and voltage output. Simulation results are included to verify theory.