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US 7,271,650 B2Granted
PWM digital amplifier with high-order loop filter
AssigneeASP Technologies
InventorWai L. Lee
Life of this patent
Estimating the term…
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, a limiter for controlling overload, and an output for outputting a pulse width modulated and amplified signal;
- the pulse width modulated and amplified signal having a magnitude value greater than a first-order loop filter over a range of frequencies.
A PWM digital amplifier for amplifying a digital signal, the digital amplifier comprising:
- a multiple input junction for additively receiving digital currents generated from input voltage signal Ei and a feedback voltage signal;
- an integrator with a integrator negative input node connected to the multiple junction for receiving a summed value of the digital currents, the integrator including an integrator positive input node connected to ground;
- a limiter for controlling overload;
- a comparator with a comparator positive input node connected to an integrator output node of the integrator and a comparator negative input node connected to a sawtooth signal generator;
- a voltage switch including a voltage switch input connected to the comparator output node;
- a multiple feedback loop junction connecting to the voltage switch output;
- a feedback branch connecting the three-way feedback loop junction to the three-way input junction;
- a passive low pass filter having an input connected to the three-way feedback loop junction;
- a speaker having an input connected to the low pass filter output.
6 more elements
A pulse-width modulated digital amplifier comprising:
- a loop filter for producing a stable loop output signal Ew from an input digital signal Ei, the loop filter including a limiter for controlling overload,
- a comparator for receiving loop output signal Ew and a pre-selected signal,
- the comparator generating a pulse-width modulated signal Ep from the pre-selected signal and signal Ew,
- a switching output stage for receiving pulse-modulated signal Ep and generating an output signal Eo;
- and
- a feedback loop for channeling a portion of the signal Eo to the loop filter input and combining with the input signal Ei.
3 more elements
Dependencies are inferred from the claim text.