Improvement in Noise Performance and Transconductance Using Positive Feedback in Bulk Driven Operational Amplifier.

Improvement in noise performance and transconductance using positive feedback approach in bulk driven operational amplifier is proposed in this paper. Downscaling of CMOS technology has compelled the supply voltage to reduce, which in turn demands the reduction in threshold voltage. To overcome the barrier of threshold, bulk driven technique is a good non-conventional approach because it require no modification in the existing structure of MOSFET. The limitation with bulk driven approach is that the transconductance of operational amplifier get reduced almost three to four times. Thanks to loop of positive feedback. The resulting transconductance is boosted to a higher value; thus, increasing the voltage gain and decreasing the input referred noise. So, concept of positive feedback is used in the design of low voltage (LV) low Power (LP) building blocks of operational amplifier using standard CMOS technology. Though amplifier is designed for power supply of 1V, it is also capable to operate at supply of less than 1V. The simulation is carried out using Mentorgraphics tools of 180 nm technology.