Design of a Low Noise High PSR Low Dropout Regulator

A low dropout regulator (LDO) with low output noise voltage and high power supply ripple rejection ratio (PSR) is described. The LDO improves the ability of power supply ripple rejection and output noise voltage suppression by improving power supply ripple rejection ratio and output noise voltage suppression of the band-gap reference and the differential amplifier. This approach is tested in 0.6 μm BiCMOS process. The results show that the PSR at 100 Hz is 75 dB and at 10 kHz is 72 dB, when the load current is 100 mA. The output noise voltage is 15 μV_RMS (100 Hz to 100 kHz).