Study and Analysis of GEIF and TIF Subthreshold Voltage Bulk-driven OTAs

This article demonstrates the exploitation of different ultra-low-voltage bulk-driven OTAs. Cascode topology is implemented to all transistors in Gm enhanced indirect-feedback bulk-driven miller OTA (GEIF OTA) and three-stage indirect-feedback bulk-driven OTA (TIF OTA) to enhance the DC-gain. All the transistors used in OTAs are modeled to operate in the weak-inversion region intending to consume very less power. The bulk-driven differential stage at the input side allows the low-voltage operation in each OTA. The dimensions of transistors are determined using the gm/Id methodology. The indirect-feedback compensation technique expands the unity-gain frequency in GEIF and TIF OTA.The conventional OTA, GEIF, and TIF OTA circuits are modeled and executed using the cadence virtuoso tool. These circuits are validated using parametric analysis such as DC-gain, phase-margin, unity-gain frequency, power consumption, and slew rate