Analog circuit design using current and transresistance amplifiers

Within the four amplifier types, voltage operational amplifier (op-amp) and operational transconductance amplifier (OTA) have been widely utilized in analog circuit design. On the other hand, the remaining two amplifiers, namely current operational amplifier (COA) and operational transresistance amplifier (OTRA), have not been received much attention until recently. However, the COA and OTRA have some advantageous properties that can be enjoyed by analog circuits. Both of them are characterized by internally grounded input terminals, leading to circuits that are insensitive to the stray capacitances. This feature also yields eliminating response limitations incurred by capacitive time constants. The output terminals of the COA are characterized by high impedance while the OTRA exhibits low output impedance. These make easy to drive loads without addition of a buffer for current mode and voltage mode circuits, which use COA and OTRA, respectively. The current differencing and internally grounded inputs of these elements make it possible to implement the circuits with MOS-C realization. In this thesis, two CMOS realizations for the COA are presented. They are basically obtained by cascading an OTRA and a dual output OTA. Current mode first order allpass filters, biquadratic filters and sinusoidal oscillators have been introduced as the applications of the CMOS COAs. Some analog circuits employing the OTRA have also been presented. Among these are first order allpass filters, all five different forms of second order filters, multifunction biquads, transimpedance type biquadratic filters and sinusoidal oscillators. OTRA based circuits for the realization of nth order voltage transfer function and fully controllable negative inductance are also included. The workability of the presented circuits has been verified by PSPICE simulation results. Some of the circuits are also tested experimentally.Keywords: analog circuit design, integrated circuits, current operational amplifiers, operational transresistance amplifiers