Investigation on the Susceptibility to RF Interference of LDO Voltage Regulators

The DC output voltage of low dropout (LDO) voltage regulators can be affected by the presence of radio frequency interference (RFI) superimposed onto the DC input terminal. This is due to the rectification of the interference carried out by the building blocks of the voltage regulator. Traditionally the problem has been addressed by adding filters at the printed circuit board level, but this requires additional components, and filters are effective on a limited frequency band. This work discusses the susceptibility to RFI of an LDO based on a traditional architecture, then a novel solution to increase its immunity is proposed. The effectiveness of the proposed approach is validated through simulations.