Amplifiers – Modulator-demodulator-type amplifier
Reexamination Certificate
2011-01-18
2011-01-18
Chin, Vivian (Department: 2614)
Amplifiers
Modulator-demodulator-type amplifier
C381S094100, C381S094500
Reexamination Certificate
active
07872522
ABSTRACT:
Noise reduction for a switching amplifier system having a differential output stage and demodulator filter responsive to complementary PWM signals includes generating in-phase PWM signals and gradually adjusting their duty cycle between a low duty cycle and the full duty cycle of the complementary PWM signals, generating full duty cycle PWM signals and gradually shifting their relative phase between in-phase and out-of-phase; and in response to a turn-on signal, adjusting the in-phase PWM signals from low to full duty cycle and shifting the relative phase from in-phase to out-of-phase, and in response to a turn-off signal shifting the relative phase from out-of-phase to in-phase and adjusting the in-phase PWM signals from full to low duty cycle for maintaining balanced charge on the demodulation filter to reduce audible noise.
REFERENCES:
patent: 4673889 (1987-06-01), Cini et al.
patent: 5805020 (1998-09-01), Danz et al.
patent: 6191676 (2001-02-01), Gabor
patent: 6384678 (2002-05-01), Berkhout
patent: 6720825 (2004-04-01), Hansen et al.
patent: 6998911 (2006-02-01), Honda et al.
patent: 7312654 (2007-12-01), Roeckner et al.
patent: 2004/0217808 (2004-11-01), Kim et al.
patent: 2005/0083115 (2005-04-01), Risbo
patent: 2006/0082352 (2006-04-01), Warita et al.
patent: 2006/0152281 (2006-07-01), May
patent: 0817371 (1998-01-01), None
patent: 1418666 (2004-05-01), None
patent: WO 00/27028 (2000-05-01), None
patent: WO 01/91285 (2001-11-01), None
Eric Gaalaas,Class D Audio Amplifiers: What, Why, and How, 40-06 Analog Dialogue, pp. 1-7 (Jun. 2006) <http://www.analog.com/analogdialog>.
Gaalaas Eric
Menard Gabriel
Analog Devices Inc.
Chin Vivian
Fahnert Friedrich
Kenyon & Kenyon LLP
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