REALIZATION OF WAVE ACTIVE FILTER USING VOLTAGE DIFFERENCING BUFFERED AMPLIFIER

Abstract

Analog filters play a key role in any modern communication, instrumentation and electronic system. Though today the entire signal processing world seems to be digital, the presence of continuous time filters can be found at every interface with analog world. With the evolution of several new active building blocks in open literature, there is a great advancement in active filter design. Voltage Differencing Buffered Amplifier (VDBA) is a recently proposed voltage mode active block which has been widely used for filtering as well as signal generation circuits. VDBA combines the features of transconductance amplifier and buffered amplifier. To meet the stringent sensitivity requirements, higher order analog filters are designed by simulating resistively terminated LC ladder. Active simulation of LC ladder is done primarily by three techniques Element replacement method, Operational simulation and wave active approach. The present work deals with the realization of higher order analog filters using wave active approach. Wave active approach offers several advantages over other techniques such as modular structure, use of lossy integrators etc. This approach is quite similar to the element replacement approach for the design of higher order filters. In this approach wave port terminator equivalents of shunt arm and series arm of a doubly terminated LC ladder are designed with the help of different active building blocks. In the present work, Voltage differencing buffered amplifier has been used to derive series and shunt arm wave equivalents. The workability of the discussed method is shown by implementing 4th order Butterworth low pass filter. Due to virtue of wave active approach a complementary high pass output response is also obtained. All the circuits presented in the dissertation have been simulated on PSPICE.