OTRA BASED CONTINUOUS TIME CIRCUITS

Abstract

The reduction of the minimum feature size of an MOS transistor for digital VLSI circuits has been ongoing for the past few decades. As the channel length is scaled down into deep sub micrometer dimensions, the lower power supply voltage is required to ensure the device reliability. To be compatible with digital VLSI technologies, analogue integrated circuits, which can operate at low supply voltages, are also receiving significant attention. This has resulted in development of various current mode analog building blocks and operational transresistance amplifiers (OTRA) is one among those. The OTRA is high gain current input voltage output device, both the input and output terminals are characterized by low impedance. OTRA being a current mode building block inherits the advantages of current mode processing, the input terminals are virtually grounded leading to circuits that are insensitive to stray capacitances. Being a current processing device the OTRA has a bandwidth independent of the device gain and is also not slew limited in the same manner as an OP-AMP. Operational Transresistance Amplifiers are used in various type of applications namely filters, oscillators, multivibrators, multiplier and squarer etc. These all designs benefit from current mode approach of OTRA in this project a systematic review of the available literature on OTRA has been presented and are further studied and implemented. These OTRA based designs are best suited for the low power and high speed applications apart from its traditional field of application.