Class D amplifier

Details Class D amplifier Class D amplifier

2007-08-14

2007-08-14

Bocure, Tesfaldet (Department: 2611)

Pulse or digital communications

Pulse code modulation

Differential

C375S254000, C341S143000

Reexamination Certificate

active

10770407

ABSTRACT:
The present invention relates to Class-D amplifiers, and in particular to bit-flipping sigma-delta modulator (SDM) implementations of such amplifiers. Such amplifiers are particularly although not exclusively suitable for audio equipment such as hi-fi and personal music amplifiers. The present invention provides a bit flipping sigma delta modulator (BF SDM) having a multiple feedback loop filter structure. The modulator comprises a quantiser coupled to a bit flipping means, a look ahead quantiser to determine the next quantiser output, and a controller which determines whether to change the output of the bit flipping circuit. The modulator comprises a feedback loop arranged to add feedback from the output of the modulator to its input. The modulator comprises compensation circuit to adjust the states of the modulator in order to correct for bit flipping of the output of the quantiser. This adjusts the input to the quantiser to correspond to an input having feedback from a non bit flipped quantiser output.

REFERENCES:
patent: 2 343 573 (2000-05-01), None
Magrath et al., “Resolution Enhancement and Dither of Sigma-Delta Modulator Digital-to-analogue Converters,” Electronics Letters vol. 31, No. 18, Aug. 31, 1995, pp. 1540-1542.
Magrath et al., “Non-Linear Deterministic Dithering of Sigma-Delta Modulators,” Institution of Electrical Engineers, 1995, pp. 1-6.
A.J. Magrath et al. “Design and Implementation of a FPGA Sigma-Delta Power DAC”,IEEE,Nov. 1997, pp. 511-521.
A.J. Magrath et al., “Power Digital-to-Analogue Conversion Using Sigma-Delta Puse Inversion Techniques”,99th Convention of the Audio Eng. Society,Oct. 1995.
J. Vanderkooy, “New Concepts in Pulse-Width Modulation”, Presented at AES 97th Convention, San Francisco, Nov. 10-13, 1994.
A.J. Magrath et al., “Performance Enhancement of Sigma-Delta Modulator D-A Converters using Non-linear Techniques”IEEE,1996.
A.J. Magrath et al., “Digital Power Amplification using Sigma-Delta Modulation and Bit Flipping”J. Audio Eng. Soc.,vol. 45, No. 6, Jun. 1997, pp. 476-487.

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