ANALOG FILTERS DESIGN USING CDBA AND CDTA

Abstract

During the last few decades, designers have used voltage mode techniques to solve several circuit design problems. A traditional operational amplifier has a bandwidth which is dependent on the closed - loop voltage gain. To overcome this problem, circuits operating in current mode are preferred. Current-mode circuits are useful for the low voltage operation In addition to the low voltage operation, popularity of current-mode circuits can be attributed to some other features such as larger dynamic range, low power consumption and higher speed.

The major goal of this work is to study, Current Differencing Buffered Amplifier (CDBA), a current mode building block and implement various signal processing and generation applications. A detailed description of CDBA including its nodal equations and different implementations has been presented in this thesis work. The Literature survey section consists of the already existing applications that have been developed using CDBA. Various existing circuits like analog filters and floating inductance etc. have been studied and implemented for verification of their results. The circuits are simulated with PSPICE. The simulation results verify that the circuit topologies using CDBAs for realizing signal generating circuits are simple, effective, flexible, versatile, and easily tunable.

In the final section a multimode Allpass filter is proposed that can operate in all modes viz transimpedance mode, transadmittance mode, voltage mode and current mode. For the above circuit, simulations have been done on PSPICE to verify their working.