Low-cost ferrite bead filters are used to suppress EMI. They are placed close to the amplifier output to minimize loop antennas. At low frequencies, ferrite beads act as 0 Ω resistors with no DC drop. However, the impedance of ferrite bead increases significantly at frequencies above 1 MHz to suppress radiation. Ferrite beads also play a significant role on the THD+N of the system. Examples of ferrite beads which have been tested and worked well with the TAS5825M device include the NFZ2MSM series from Murata.

The trade-off of ferrite beads is their impedance and rated current. If the rated current can meet the system requirements, larger impedance means larger EMI margins for the EMI, especially for the 5 MHz to 50 MHz frequency range. 300 ohm @ 100 MHz is a typical value, which can pass EMI in most applications.

The trade-off of capacitors is their capacitance and idle current. Larger capacitance leads to larger idle current. Using 2.2 nF instead of 1 nF capacitors is helpful in the 5 MHz to 100 MHz range.