A Low-Noise High-Voltage Rail-to-Rail Operational Amplifier with Gain Stabilization and Slew-Rate Enhancement

This paper proposes a low-noise high-voltage rail-to-rail operational amplifier based on BCD process. For the protection of low-voltage devices in input stage, this paper proposes a common-mode voltage following circuit which not only realizes the stable performance of low-voltage input devices but also improves the gain under full supply voltage. In order to improve the response speed of large signals, this paper proposes a dynamic slew-rate enhancement technology to achieve the characteristics of low quiescent current and large slew-rate. Besides, this paper optimized the low-frequency noise of the proposed architecture. The circuit uses 180nmBCD process, and the simulation results show that after applying the above technology, the supply voltage range is 3.5-36 V, the quiescent current is about 0.99 mA, the equivalent input noise is 0.82 uVp-p, the slew-rate is 15.2 V/us, the setting time is 0.66 us and the open loop gain is 135 dB in full supply voltage range.