A Robust Local Positive Feedback Based Performance Enhancement Strategy for Non-Recycling Folded Cascode OTA

In this study, a local positive feedback technique is proposed to enhance the performance of the folded cascode (FC) operational transconductance amplifier (OTA) when working in its saturation region. The enhanced FC-OTA has a higher gain bandwidth (GBW), higher DC gain and higher slew rate (SR) over its conventional counterparts and popular recycling FC-OTAs. The proposed enhanced FC-OTA is implemented by reusing the current generated by the input transistors through the proposed local positive feedback loop to provide additional transconductance and negative resistance. It is then fabricated with SMIC 180nm process. To verify the effectiveness of the proposed FC-OTA performance enhancement strategy, extensive mathematical analysis, small-/large-signal stability analysis, simulation and experimentation are thoroughly investigated in this study. Simulation and experimental results agree well with the theoretical analysis and the expected performances, which corroborates the control design.