Looking for a clean power supply for a sensitive analog circuit? Analog Devices describes the sources of noise in LDO voltage regulators, and provides some examples to limit and combat the noise.
In general, LDO noise comprises two components: intrinsic, or internally generated noise, and extrinsic, or externally generated noise.
- Thermal and 1/f noise are the main contributors to internally generated noise and are a function of the design and semi-conductor technology of the LDO.
- Extrinsic noise has many sources, but the most common is the noise on the input power supply to the LDO.