Single-Ended and Fully-Differential Current-Input Current-Output Universal Frequency Filter with Transconductace and Transresistance Amplifiers

摘要

A new filtering structure of the 2nd-order universal frequency filter is presented. The proposed filter operates in a current-input current-output form and it is designed using signal-flow graphs (SFG) method. Operational transconductance amplifiers (OTAs), current follower (CF) and operational transresistance amplifier (OTRA) are used in the proposal. The filter possesses ability to adjust the pole frequency and quality factor of the filter without violating each other. All output responses are taken directly from high-impedance outputs of used active elements. The proposal requires only two external passive elements, namely two capacitors which are both grounded. The proposed filter has been also designed in its fully-differential form. The proper function of the proposed S-E and F-D filter is verified by PSpice simulations and in case of the S-E filter also by experimental measurements. Demonstrations of possibility to tune the pole frequency and quality factor of the proposed S-E and F-D filter are illustrated in the paper. Subsequently, comparison of simulations of S-E and F-D structures of the proposed filter and comparison of results of the S-E filter obtained from simulations and experimental measurements are also included.