This paper describes the design of Two Stage Operational Amplifier using three structures and calculation of its various parameters. The three basic designs include CMOS, Hybrid of CMOS and DTMOS, and full DTMOS, which operate at 2.5V power supply and 0.18um technology. In this paper, simulation curves are computed for its different characteristics such as Gain, PM, ICMR, CMRR. Simulation has been carried out in PSPICE tool. All the three design are application specific. The basic CMOS based 2 stage op-amp provides high open loop voltage gain and rail to rail output swing. First proposed design is the Hybrid of CMOS and DTMOS which provides additional gain, increased CMRR and higher phase margin. The second proposed design is Full DTMOS based 2 Stage op-amp which can be used for low power applications as DTMOS is the best alternative for implementation of low power circuits.