Class d amplifier with pulse width modulation and a very low power consumption
AssigneeG/N Netcom A/S
InventorsLars Backram, Hans-Erik Backram, Börje Gustafsson
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Abstract
The invention concerns a class D amplifier in which a high-frequency reference signal is pulse width modulated by an input signal, such as an audio signal, and in which there are generated a pair of bipolar pulse drive signals, comprising an error generator which forms a signal with an average value which corresponds to the DC component of the pulse drive signals, and which is fed back to the pulse width modulator for the adjustment of the modulator. The high-frequency reference signal is generated from a first clock signal, and the individual pulses of the respective pulse drive signals are controlled via a second clock signal which is derived from the first clock signal.
Claims5
A class D amplifier for the amplification of an input signal, e.g. an audio signal, comprising a pulse width modulator in which a high-frequency reference signal (E) is pulse width modulated by the input signal, a difference generator in which there is generated a pair of bipolar pulse drive signals (I, J) with duty cycles corresponding to the magnitude of the input signal for a given time, and an error generator which by the two pulse drive signals forms a signal corresponding to the average DC component of the pulse drive signals, and which is fed back to the pulse width modulator for the adjustment of the modulator, so that the amplified AC signal's average DC part moves towards zero, characterized in that
- the high-frequency reference signal is generated from a first clock signal (A), and in that
- either the leading edge or the trailing edge of the individual pulses in the respective pulse drive signals (I, J) are controlled to occur synchronously with a second clock signal (C) derived from the first clock signal (A).
Dependencies are inferred from the claim text.