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Custom geometries solutions for audio industry - Aerospace & Air Transport
Class D amplifiers typically use a low-pass LC type filter to attenuate the switching noise in the output waveform while passing the audio signal to the loudspeaker. So it is important that engineers design and specify the correct L-C filter values in addition to choosing the correct LC components for the amplifier to minimize losses and harmonic distortion. Class D Amplifier uses pulse width modulation technique to sample audio signal level for amplification. Audio input is typically compared to a high frequency (>250kHz to MHz) sawtooth to produce a square wave signal with equal amplitude and duty that varies with signal level. The high frequency pulses can then be amplified with little power loss.
To recreate the audio signal, Class D amplifiers typically use a low-pass LC type filter to attenuate the high frequency switching noise in the output waveform while passing the audio signal to the loudspeaker.
The output filter inductor has to handle the level of audio frequency signal without saturation, while providing high impedance to high frequency noise with minimal core loss and distortion.
For decades, audio engineers have exclusively specified Micrometals iron powder cores for their filter designs, in particular our exclusive Mix-2, which, due to its low permeability, exhibit very linear frequency response, and exhibits low losses at high sampling frequency due to intrinsic properties as well as lower operating flux density as a result of higher winding turns.
Typical applications with inductive Components:
- AC Inductor with ripple – DC-AC Inverter Output Filter
When designing the filter inductor for class-D amplifiers engineers need to be certain that the DC current rating of the filter inductors be greater than or equal to the maximum current that it will experience and that the selected core material does not adversely affect the amplifier`s harmonic distortion and incur very low hysteresis losses.