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US 7,345,532 B2Granted
PWM digital amplifier with high-order loop filter
AssigneeASP Technologies
InventorWai L. Lee
Life of this patent
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Abstract
An improved PWM amplifier is disclosed that uses multiple integrators in the loop filter to provide high loop gain across the frequency band-of-interest. The frequency characteristics of the loop filter are optimized to distribute large loop gains across the entire band to provide large suppression of noise and distortions generated in the modulation and output stages.
Claims10
A method for amplifying a digital signal including the steps of:
- generating an integrated signal Ew by integrating an additively combined signal, the additively combined signal is an additive function of an input signal Ei and a digital feedback signal Ef;
- producing a pulse width modulated digital signal Ep by modulating integrated signal with a periodic signal Ec, and
- generating a digital output signal Eo by driving pulse width modulated digital signal Ep to a peak voltage, feedback signal Ef comprising a portion of output signal Eo;
- and
- producing a filtered output signal by low pass filtering output signal Eo, the integrated signal having a magnitude value no less than 40 dB over a range of frequencies, the range of frequencies having a bandwidth greater than 1 kHz.
2 more elements
A method for amplifying a digital signal including the steps of:
- generating an integrated signal Ew by integrating an additively combined signal, the additively combined signal is an additive function of an input signal Ei and a digital feedback signal Ef;
- producing a pulse width modulated digital signal Ep by modulating integrated signal with a periodic signal Ec, and
- generating a digital output signal Eo by driving pulse width modulated digital signal Ep to a peak voltage, feedback signal Ef comprising a portion of output signal Eo;
- and
- producing a filtered output signal by low pass filtering output signal Eo, the integrated signal having a magnitude value no less than 20 dB over a range of frequencies, the range of frequencies having a bandwidth of at least 30 kHz.
2 more elements
A method for amplifying a digital signal including the steps of:
- generating an integrated signal Ew by integrating an additively combined signal, the additively combined signal is an additive function of an input signal Ei and a digital feedback signal Ef;
- producing a pulse width modulated digital signal Ep by modulating integrated signal with a periodic signal Ec, and
- generating a digital output signal Eo by driving pulse width modulated digital signal Ep to a peak voltage 2V+, feedback signal Ef comprising a portion of output signal Eo;
- and
- producing a filtered output signal by low pass filtering output signal Eo, the integrated signal having a magnitude value greater than a first-order loop filter over a range of frequencies, the range of frequencies having a bandwidth greater than 100 kHz.
2 more elements
Dependencies are inferred from the claim text.