Attenuating non-linear noise in an amplifier with alternating DC-offset correction

摘要

An amplifier may include two or more pulse-width modulators controlling respective sets of switches to produce an amplified version of a source signal. A positive DC-offset based on the source signal may be applied to the pulse-width modulator controlling one respective set of switches, and an equal value negative DC-offset may be applied to the pulse-width modulator controlling the other respective set of switches, to provide an effective offset between the respective points in time of the rising/falling edges of the different pulse-width modulated control signals. The addition of alternating positive and negative DC-offset values doesn't affect the output load, and doesn't degrade the signal. The DC-offsets may be added at a frequency selected to be beyond the signal baseband, and the value of the small input signal level may be determined using an RMS level comparator or similar measurement technique.

主权项

1. A method of attenuating non-linear noise in an open-loop amplifier, the method comprising:
deriving a first representative signal and a second representative signal from a source signal; obtaining a first intermediate signal by deriving a positive DC-offset from the source signal, and adding the positive DC-offset to the first representative signal; obtaining a second intermediate signal by deriving a negative DC-offset from the source signal, and adding the negative DC-offset to the second representative signal, wherein the negative DC-offset and the positive DC-offset have a same absolute value; deriving a first control signal from the first intermediate signal, and a second control signal from the second intermediate signal; and obtaining an amplified version of the source signal by controlling a first set of switches with the first control signal, and a second set of switches with the second control signal; the method further comprising alternating between:
adding the positive DC-offset to the first representative signal while adding the negative DC-offset to the second representative signal; andadding the positive DC-offset to the second representative signal while adding the negative DC-offset to the first representative signal.