CONTINUOUS TIME CIRCUITS BASED ON CDBA

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 popularity of current-mode circuits has resulted in emergence of various current mode analog building blocks. Current Differencing Buffered Amplifier (CDBA) is one of them. The CDBA being a current processing analog building block inherits the advantages of current mode technique. In addition, it is free from parasitic capacitances as its input terminals are internally grounded. Thus this active block is appropriate for high frequency operation. It provides further flexibility of design as both current and voltage outputs are available at high and low impedance respectively. In this work a detailed description of CDBA along with its various implementations available in literature is presented which is followed by simulation of various signal processing and generation applications already existing in literature such as analog filters, floating inductor, multiplier, etc. Finally four circuit designs namely a PID controller, a monostable multivibrator, multi output filter and a grounded inductor using CDBA, are proposed in this work. The workability of the proposed circuits is verified through PSPICE simulation using 0.18μm CMOS process parameters.