Designs, simulations and experiments of the CFOA-based analog filters

In this thesis, a total of nine active filters, three first-order and six second-order with current feedback operational amplifier (CFOA)-based voltage-mode are designed. Simulations of the designed filters are made through the SPICE program. In the internal structure of some designed circuits, 0.18 µm TSMC CMOS technology parameters are used, while 0.13 µm IBM CMOS technology parameters are used in others. Additionally, experiments to see the performance of the designed filters are carried out using one AD844 instead of one CFOA. The first of the designed first-order filters is single-input multiple-output (SIMO), the second and third ones are multiple-input single-output (MISO) universal filters. While the first circuit contains two CFOAs, the second and third ones contain one CFOA and one unity gain inverting amplifier. The designed first-order filters have high input impedances. In addition, the designed first circuit has low output impedances for high-pass filter (HPF) and all-pass filter (APF) responses, and the other two circuits have low output impedances for all the responses. While the first circuit contains a grounded capacitor, the second one consists of a minimum number of passive elements. The HPF and APF responses of the first circuit and the low-pass filter response of the third circuit have a gain. However, there is one passive element matching condition for the APF responses of the first and third circuits. The first of the designed second-order filters is SIMO, the second, third, fourth and fifth ones are MISO and the sixth one is multiple-input multiple-output (MIMO). The second-order MISO filters are universal, while the SIMO and MIMO ones are multifunction. While the first four of the designed second-order filters contain two CFOAs, the fifth circuit contains one CFOA and one voltage follower. The sixth circuit is designed with three CFOAs. The last four circuits have the feature of orthogonal controllability. While all the six designed second-order filters have low output impedances, five of these circuits have some high input impedances. Additionally, some of these filters have a gain. However, in some circuits, there is a single passive element matching condition for the APF responses.