Keeping Power Supply Noise Away From Analog Circuits with a Linear Regulator's PSRR Specification

Here we have a video from our sister company ForceTronics that explains one of the key reasons why it is good to have linear regulators between our sensitive analog circuits and switch based power sources. Of course the main job of a linear regulator is to create a stable regulated DC level. But they also have the ability to reject or attenuate noise and ripple on a DC level so it does not reach our sensitive analog circuit. The linear regulator's ability to attenuate noise and ripple is defined by its power supply rejection ratio or PSRR specification (sometimes just called ripple rejection). The following video provides a detailed explanation on the PSRR spec and how to understand it. 

Just to help reinforce some of the points from the video, below you will find three PSRR or ripple rejection charts below all for the same linear regulator. These charts clearly show how the PSRR curve of a linear regulator can not only vary based on load current, but also the input voltage level and bypass capacitors values used.