关键词: 低压差线性稳压器, 高阶带隙, 斩波调制, 缓冲阻抗衰减, 低噪声

Abstract: The noise performance of the low-dropout linear regulator (LDO) mainly depends on its reference voltage. Based on the TSMC 180 nm CMOS process, a high-order temperature-compensated bandgap reference circuit is designed to provide a low-noise, low-temperature-drift reference voltage for the LDO. In this design, chopping modulation technology and a notch filter are adopted to achieve low noise performance, and a super source follower is designed as an impedance attenuation circuit to enhance circuit stability and further suppress noise. The high-order temperature compensation circuit, the chopping modulation circuit, and the buffered impedance attenuation circuit are made to work together to ensure high signal purity from the reference source to the output stage and to achieve low noise characteristics. Simulation results show that, within the temperature range of -45-120 ℃, the overall circuit temperature coefficient is  obtained as 2.9×10^-6/℃. When the frequency is set to 1 Hz, the LDO noise is reduced from 159.67 µV/ to 3.69 µV/, and the issues of op-amp offset and 1/f noise are significantly improved. Under both light-load and heavy-load conditions, the system is shown to have good stability.

Key words: low-dropout linear voltage regulator, high-order bandgap, chopping modulation, buffered impedance attenuation, low noise