Design of Ultra Low Drop-out Regulator for Audio Devices

Low Drop Out (LDO) regulators are widely used in battery-powered portable electronic devices because of their low dropout, low quiescent current and large load current characteristics with minimum heat losses. The proposed ultra LDO regulator architecture uses a telescopic error amplifier and single stage charge pump with non-over lapping clock logic. The telescopic cascode error amplifier with NMOS pass element output stage increases the Power Supply Rejection Ration (PSRR) of the ultra LDO regulator and also reduces the area by using internal compensation. The non-over lapping clock logic minimizes the charge pump losses, thus enabling the ultra-low drop out. The ultra-low dropout regulator design has been analysed its performance against the specification requirement for audio device applications and implemented in 180 nm CMOS technology. The results show the proposed ultra-low drop out regulator is capable of delivering 1.5V regulated output with 200 mA load current over supply voltage range of 1.95 V to 1.55 V with a bandwidth of 20 kHz. The drop out voltage is only 50 mV at maximum load current (200 mA) for minimum supply voltage. The load regulation is 0.1 mV/mA and line regulation is 1 mV/100mV. The ultra LDO regulator has a PSRR of-56 dB at 20 kHz. The area of the ultra low drop out regulator is 0.1 mm2.