In this paper a CMOS operational amplifier is presented. A CMOS operational amplifier is presented here which is operating at 2V power supply and 1microamp input bias current at 0.8micrometer technology using nonconventional mode of MOS transistors and whose input is dependent on bias current. The unique behavior of the MOS transistors in sub threshold region allows a designer to work at low input bias current. It also allows operating at low voltage. While operating the device at weak inversion results low power dissipation but dynamic range is degraded. Optimum balance between power dissipation and dynamic range results when the MOS transistors are operated at moderate inversion. In comparison with the reported low power, low voltage op-amps at 0.8micrometer technology, this op-amp has very low standby power consumption with a high driving capability and operated at low voltage. operating the device in moderate version is a good solution. Also operating the device in sub threshold region not only allows lower power dissipation but also a lower voltage operation is achieved. The proposed op-amp is a simple two stage single ended op-amp. The input stage of the op-amp is a differential amplifier with an NMOS pair. Operational Amplifiers, or Opa-mps as they are more commonly called, are one of the basic building blocks of Analogue Electronic Circuits. Operational amplifiers are linear devices that have all the properties required for nearly ideal DC amplification and are therefore used extensively in signal conditioning, filtering or to perform mathematical operations such as add, subtract, integration and differentiation.