Which capacitors are best for Class D amplifier supply bypassing?
Ceramic chip capacitors are the best choice for power supply bypass on Class D amplifiers. Their low ESR and excellent high-frequency characteristics improve audio performance and help lower EMI. If the Class D amplifier is located far from the power supply, some additional bulk capacitance should be included. The most cost effective for this is low-ESR aluminum electrolytic capacitors, although general-purpose aluminum electrolytic capacitors are often used. Some engineers will use multiple bypass capacitors to help with EMI. Located closest to the power supply pin is a small, 0.1-µF or smaller, bypass capacitor, with a larger value, such as 1 µF or greater located next down the line. General practice is to make these two capacitors at least ten times different in value to avoid a resonance band.
