© 2014 IJIRT | Volume 1 Issue 7 | ISSN: 2349-6002 IJIRT 101230 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 295 SIGNAL PROCESSING CIRCUITS USING OPERATIONAL TRANCONDUCTANCE AMPLIFIERS Swati Sharma, Manish Kumar, Rohan Chaudhary Department of Electrical and Electronics Engineering Dronacharya College of Engineering,Gurgaon Abstract-A number of techniques and circuits are available in literature for designing various signal processing circuits suitable for VLSI implementation. Some of the approaches and circuits widely investigated so far are g m -C circuits, switched capacitor circuits In principle, all of them can be employed to devise fully integratable implementation in BIPOLAR, CMOS, and Bi-CMOS technology. Recently some work has been done on employing BJT and MOSFET based current mirrors as alternating building blocks, in contrast to more complex building blocks employed in the above mentioned approaches. This paper work has investigated the state of the art of this technique and has explored the various possible options available. A critical examination based upon the rigorous analysis and/or PSPICE simulation is aimed and possible attempts will be made to search for a new design method for circuit configuration. In this paper attention was focused on the realization of voltage-mode building blocks such as voltage adders and voltage integrators (lossy and lossless) which forms the major constituent for implementing active filters. As an example to demonstrate the realization procedure, voltage-mode second order filters and TOW THOMAS Biquad obtained by cascading lossy and lossless voltage integrators and KHN Biquad filter cascading two lossy integrators. All the realized circuits were tested using SPICE and the results thus obtained were in accordance with the theortical values. Index Terms- OTA, DVCCS I. INTRODUCTION Operational Transconductance Amplifiers (OTAs) have become available as an off-the- shelf item in the monolithic IC form. It is differential voltage controlled current source (DVCCS), i.e. it produces output current proportional to the differential input voltage, and has an extra control terminal for controlling its transconductance. Besides having attractive realization features offered by an operational amplifier (OA), the OTA additionally provides excellent electronic tunability by virtue of its highly linear transconductance versus bias current relationship, for over four decades. This has given great impetus to active circuit realizations using OTAs instead of OAs, particularly, in applications where electronic tunability forms an important consideration In modern communication and instrumentation system, active networks are extensively being used in the realization of filters, oscillators, voltage controlled oscillators, phase shift oscillators, etc .Among them active RC ones using OAs as the active device have gained great prominence due to their reliable, stable and low sensitivity performance at reasonable cost. In addition, they (active RC circuits) enjoy good prospects for integration. Over the last few decades, it has been shown that the OTAs, with their excellent electronic tunability, can conveniently realize electronically tunable filters and oscillators. This feature, along with the availability of OTAs, has made them a strong rival to the OA, particularly in applications where electronic tunability is considered an important criterion in the filter design.In some applications, such as, music synthesis, automatic control, speech synthesis, independent electronic tuning of the filter parameters is needed. The use of programmable integrators (PIs), based on OTAs, instead of analogue voltage multipliers and fixed integrators has many advantages. The transconductance versus amplifier bias- current relationship of an OTA is highly linear and has been so far over four decades. Hence, electronic control of filter parameters, such as, the pole-frequency, the pole-Q and the absolute bandwidth, are conveniently possible through the bias-current over many decades of tuning range.