In the past, tantalum and aluminum electrolytic capacitors were commonly used in electronic devices, but in recent years they have been replaced with ceramic capacitors due to product miniaturization, reliability problems, etc.
With the shift toward multifunctionality and silencing in electronic devices, previously unnoticed "acoustic noise (sound)" caused by ceramic capacitors is becoming one major design issue in laptop PCs, smartphones (mobile phones), car navigation systems, wireless charging, and other power supply circuits.
In laptop PCs, "acoustic noise (sound)" caused by ceramic capacitors used in battery lines sometimes becomes a problem.
Because the internal operation of the laptop PC changes when the operation mode is changed from a sleep state/standby screen or other mode, the magnitude of the "acoustic noise (sound)" changes according to the operation mode, and the acoustic noise is also heard differently.
This document introduces measures to address "acoustic noise (sound)" due to capacitors in laptop PC battery lines, a method of evaluating acoustic noise, and the mechanism by which such noise occurs.