This paper presents a low dropout regulator (LDO) with a wide input voltage range
and high power supply rejection (PSR) for Hall sensor front-end circuits, which is
fabricated with a 0.18 𝜇m BCD process. A topology in which a closed-loop charge
pump biases the gate of two-stage cascode NMOS pass transistors is proposed to
increase immunity to Electro-Magnetic Interference (EMI) capability for automotive
applications. Furthermore, a power-down protection circuit is proposed to maintain
the reliability of the system, and a novel implementation of the charge pump unit is
presented to improve the influence of the body effect. Detailed derivation regarding
the analyses of the simplified small-signal model of the closed-loop charge pump,
the loop stability, and the PSR at various frequency bands is given. Simulation and
measurement results show that the proposed LDO can operate with the input voltage
from 5 V to 40 V, providing up to 60 mA current drive capability, and its minimum
operating voltage is 2.5 V with a 10 mA load capacity. Moreover, results verify that
measured PSR is better than -45 dB at 1.5 kHz, and measured PSR is better than -
30 dB at 15 MHz. The results confirm that the obtained parameters of line and load
regulations are significantly improved to 1.86 mV/V and 1.75 mV/mA, respectively.