A Local Positive Feedback Loop-Reused Technique for Enhancing Performance of Folded Cascode Amplifier

A current-reused folded cascode operational transconductance amplifier (OTA) using a local positive feedback (LPFB) technique has been proposed in previous literature, which does not achieve maximum unity gain-bandwidth (GBW). Besides, the stability of LPFB in the LPFB OTA is limited by local common mode feedback (LCMFB) resistors. Based on the analysis, a local positive feedback loop-reused (LPFBR) technique is proposed to improve the performance of conventional LPFB OTA. For a fair comparison, both conventional and proposed OTAs working at saturation region are designed and simulated in SMIC 0.18 μm process. The simulated results demonstrate that the proposed LPFBR OTA has almost 10.5 times the bandwidth and maintains stability compared to that of the conventional LPFB OTA under the condition that LCMFB resistors are increased by a factor of 10.