What causes inductor saturation?

Inductor core saturation occurs when the magnetic flux generated by the coil's current becomes so high that all the magnetic domains within the core material become fully aligned. Once all domains are aligned, the core cannot support any additional magnetic flux. When a core reaches this saturated state, any further increase in current will not yield a corresponding increase in the magnetic field. This causes the coil's inductance to drop drastically and can lead to severe signal distortion, excessive heating, and potential circuit failure. Saturation is driven by the amount of magnetic flux, which correlates directly with current, not by the operating frequency. Furthermore, permittivity is a property of capacitors (dielectrics), whereas permeability relates to magnetic cores.