Nearly every device that sends sound to a speaker requires an audio amplifier. With the explosive growth of consumer electronic devices,
usage has increased dramatically. Audio amplifiers are used in everything from car and home stereos, personal digital assistants (PDAs), cellphones and portable music devices such as CD and MP3 players.

An important aspect of the audio amplifier circuit is the output RF filter, required to suppress RF interference produced by fast output transitions of the amplifier.[1] Early techniques for filtering the amplifier output in car stereos used traditional through-..hole type feedthru capacitors. Over time, circuit designers have changed from through-hole type to surface mount chip feedthru capacitors or chip ferrite beads to lower costs. These new components add DC resistance to the audio circuit, which can increase power consumption and shorten battery life in handheld devices. This article will show how to use a single X2Y® bypass capacitor to improve audio amplifier output performance by removing the DC resistance. The solution also lowers system cost through component reduction.

Car Audio
In the past, many in the automotive industry used multilayer ceramic through-hole feedthru capacitors to filter the audio amplifier output in car radios….

Download RF Filtering for Audio Amplifier Circuits.pdf