Nxp B.v.

Iain Mosely

Matthias Wendt

F Javier Esguevillas

Georg Sauerländer

Thomas Dürbaum

Heinz Willi Van Der Broeck

Recently, the use of class-D audio amplifiers has become more and more widespread. In contrast to the generally employed class-AB linear amplification technology, class-D allows for improved efficiency. However, the class-D principle is known for its poor distortion characteristics. According to the present invention a digital amplifier () is provided for converting an audio signal to a power output, comprising a ripple suppression circuit () for suppressing voltage ripples in a supply voltage supplied to the bridge circuit with () at least one pair of switches. The ripple suppression circuit () suppresses ripples in the supply voltage supplied to a switch in the bridge circuit (), which has been found to cause a major part of the distortions in the output signal of the digital amplifier ().

Digital amplifier

Recently, the use of class D audio amplifiers has become more and more widespread. In contrast to the generally employed class AB linear amplification technology, class D allows for improved efficiency. However, the class D principle is known for its poor distortion characteristics. According to the present invention, switching delays of the end stage () are measured and used for compensating distortions caused by the dead time of the end stage (). This is done by modifying the switching delay of the power stage. In this way, the output pulse duration is corrected to reflect the input duty cycle. Advantageously, variations in the switching-time due to device property spread, aging, current and temperature may be compensated.

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Cleveland, United Kingdom

Iain Mosely