REALIZATION OF TIMER CIRCUIT USING OTRA AND ITS APPLICATION

Abstract

The main objectives of this project are to study and design a simple, portable, and low cost timer and the limitations of the commercially available 555 Timer has been overcome. The presented topology uses two operational transresistance amplifier (OTRA). The proposed circuits are insensitive to parasitic capacitances and resistances due to internally grounded input terminals of OTRA. Low output impedance of the configuration enables the circuits to be cascaded without additional buffers. The OTRA is suitable for analog VLSI applications since it does not suffer from constant gain bandwidth product. Hence, it can exhibit wide bandwidth at high gain values. The operational transresistance amplifier (OTRA) is an amplifier which provides an output voltage with inputs as two differential currents. Thus, it is a current controlled voltage source. The transresistance required is very high so as to realize open loop circuits such as comparator and closed loop circuits such as filters. With the help this timer circuit similar application can be design as with the 555 timer circuit overcoming the drawback. Under this project by using this timer circuit three applications Astable multivibrator, monostable multivibrator and pulse width modulator circuits have been implemented. The performance of the proposed Timer IC circuits is verified through PSPICE simulation using 0.5 μm CMOS process parameters provided by MOSIS (AGILENT).