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.
Claims24
A PWM digital amplifier for amplifying a digital signal, the digital amplifier comprising:
- a pulse width modulator section, the pulse width modulator section having an input portion for receiving an input digital signal and an output for outputting a pulse width modulated and amplified signal;
- the pulse width modulated section characterized by the pulse width modulated and amplified 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.
A pulse width modulated digital amplifier for amplifying an incoming digital signal Ei and generating an output digital signal Eo, the digital amplifier including
- a digital signal amplification section for digitally amplifying a pulse-width modulated digital signal;
- and
- a feedback loop for carrying a portion of the output digital signal Eo;
- the digital signal amplification section characterized by the pulse width modulated 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.
A PWM digital amplifier for amplifying a digital signal, the PWM digital amplifier comprising:
- a pulse width modulator section, the pulse width modulator section having an input portion for receiving an input digital signal and an output for outputting a pulse width modulated and amplified signal Eo;
- and
- a feedback loop for channeling a portion of the signal Eo external to the loon filter through a passive element and combining with the input signal Ei,
- the pulse width modulator section including
- a multi-stage loop filter for producing a stable loop output signal Ew from an input digital signal Ei,
- a comparator for receiving loop ouput signal Ew and a pre-selected signal, the comparator generating a pulse-width modulated signal Ep from the preselected signal and signal Ew, and
- a switching ouput stage for receiving pulse-modulated signal Ep and generating the pulse modulated and amplified signal Eo;
- the pulse width modulator section characterized by the pulse width modulated and amplified 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.
Dependencies are inferred from the claim text.