Voltage regulator with high accuracy and high power supply rejection ratio

摘要

A voltage regulator circuit with high accuracy and Power Supply Rejection Ratio (PSRR) is provided. In one embodiment, an op-amp with a voltage reference input to an inverting input has the first output connected to a PMOS transistor's gate. The PMOS transistor's source and drain are each connected to the power supply and the voltage regulator output. The voltage regulator output is connected to an NMOS transistor biased in saturation mode and a series of two resistors. The non-inverting input of the op-amp is connected in between the two resistors for the first feedback loop. The op-amp's second output is connected to the gate of the NMOS transistor through an AC-coupling capacitor for the second feedback loop. The op-amp's first output can be connected to the power supply voltage through a capacitor to further improve high frequency PSRR. In another embodiment, the role of PMOS and NMOS transistors is reversed.