A Compact High-Accuracy Rail-to-Rail CMOS Operational Amplifier

A compact high-accuracy rail-to-rail CMOS operational amplifier (Op-Amp) is presented using strong inversion techniques to achieve power consumption of 90μW under 1.8V supply voltage. Two complementary differential pair techniques and one-versus-three current mirror compensation techniques are adopted to realize wide input dynamic range, while the output stage provides rail-to-rail output drive through the use of resistor-compensation circuits (RCC) and self-regular circuits (SRC). Simulation results demonstrated that the active area is only 0.001mm2 and the transconductance variation can be restricted to ±5% hence the accurate of common-mode rang (99.9%) was improved as well as the total harmonic distortion.