Programmable 1 A ultra-low dropout LDO regulator for high-resolution camera sensors

Abstract

In this article, design and realization of a high-performance linear low dropout regulator (LDO) capable of supplying 1 A of output current, designed and fabricated in 180 nm BCD technology of STMicroelectronics company, is described. The main purpose of this device is providing a stable output voltage for supplying high-resolution sensors of cameras in cellphones. The LDO is equipped with a big N-channel power transistor allowing an ultra-low dropout voltage around 50 mV at the maximal load current of 1 A even with a very low level of the output voltage of only 0.4 V. These features make the device suitable as a block following buck switching converters. Emphasis has been laid on assuring 1% accuracy of the output voltage across full temperature range and line and load conditions, very low quiescent current around 32 μA, necessary for battery powered applications such as cellphones, good transient response and a high power supply rejection ratio (PSRR) of more than 85 dB at 1 kHz. This combination of high-level parameters stands for an extraordinary device. The proposed LDO is a programmable device which means that the output voltage (up to 100 voltage versions in total) and other functions can be set via post-package electrical trimming. Last but not least, an efficient design for testability (DFT) is implemented in order to reduce the failed parts to a very low level, guaranteeing the highest quality level needed in the market.