A Low Noise LDO with Pre-amplified Stage and Base-current Compensation

This paper presents a low noise LDO with pre-amplified stage and base current compensation with low noise and high transient response. In this proposed LDO, a pre-amplification structure, where a BJT pre-amplified stage is added before the conventional error amplifier (EA), is employed to reduce the 1/f noise of the EA to improve the LDO noise performance. Owing to the existence of the BJT base current, the base current compensation is added before the pre-amplified stage to ensure the output voltage accuracy. In this paper, a charge release path is added to the output to improve the LDO transient response. The chip was implemented in 0.18μm CMOS process. The integrated noise is approximately 50μV in the range of 10 Hz to 100 kHz at the input voltage of 1.4 V and the load current of 50 mA. The output noise is 0.8μV at a frequency of 10 Hz. The LDO output voltage stabilizes within 6.8μs as the load current is abrupt from 50 mA to 1 mA.