The Study And Design Of A BiCMOS Low Dropout Regulator

Low dropout linear regulator, LDO is a DC linear regulator whose input voltage is larger than output voltage. It owns fast input output response, low output noise, fewer external components, convenient usage, and low cost. Therefore it is applied broadly in automobile electronic equipments, portable communications equipments, industrial and medical fields. Recently with the development of portable electronic products, it is necessary to reduce dropout voltage and quiescent current to extend battery life, reduce power consumption, and improve efficiency of the LDO.On the base of analysis design principle, we proposed a low dropout regulator using BiCMOS technology which benefits from the speed of bipolar devices and the low power consumption of MOS devices. Additionally this LDO has internal thermal and current limiting protection. Beginning with the system stability. After analyzing and optimizing error amplifier, bandgap reference and the pass element, the designed LDO without protection and enable circuits was simulated on the 0.6μm BiCMOS Process. Hspice results show that it has a good frequency characteristic after added two Miller capacitors. Finally the whole system including protection and enable parts was simulated. The outcomes indicate that under the typical conditions, 4.3V power voltage, 25℃and 150 mA load current, the typical dropout is 120mV, the quiescent current and the output noise are only 15.43uA and 67 uVRMS respectively. And in the standby mode, the quiescent current is less than 0.04uA typically. The regulator has a wide range of power supply from (3.3+ )V to 10V with low power dissipation and low noise. VDO...