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US 8,525,593 B2Granted
Circuit and method for amplifying a digital signal
AssigneeSTMicroelectronics (Shenzhen) R&D Co. Ltd
InventorQiYu Liu
Life of this patent
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Abstract
An amplifier circuit includes an amplifier unit that is configured to receive an input signal and generate a switching output signal. A level shifter is configured to shift the amplitude of the input signal to have a shifted amplitude that is proportional to a peak-to-peak amplitude of the switching output signal.
Claims21
An amplifier circuit, comprising:
- an amplifier unit configured to receive a switching input signal and to generate a switching output signal;
- and
- a level shifter configured to shift an input signal to generate the switching input signal having a shifted amplitude proportional to a peak-to-peak amplitude of the switching output signal;
- wherein an amplitude of the input signal is shifted by the level shifter to a value approximately equal to a ratio of an amplitude of the switching output signal divided by an input to output voltage gain applied by the amplifier unit to generate the switching output signal from the switching input signal.
1 more element
An audio amplifier circuit, comprising:
- a PWM modulator configured to convert an analog audio signal into a PWM signal having a first amplitude;
- a digital amplifier circuit, comprising:
- a negative feedback class-D amplifier unit configured to receive a level shifted PWM signal and generate a switching output signal;
- and
- a level shifter configured to shift the PWM signal from the first amplitude to a shifted amplitude having a value approximately equal to a ration between the a peak-to-peak amplitude of the switching output signal and a voltage gain of the negative feedback class-D amplifier unit;
- and
- a low pass filter configured to filter the switching output signal so as to output a regenerative analog audio signal.
4 more elements
A method comprising:
- negative feedback class-D amplification of a shifted input signal to generate a switching output signal;
- shifting an amplitude of an input signal to a value proportional to the peak-to-peak amplitude of the switching output signal;
- wherein shifting comprises shifting the amplitude of the input signal to a value approximately equal to a ratio between the peak-to-peak amplitude of the switching output signal and a voltage gain of the negative feedback class-D amplification.
A circuit, comprising:
- a level shifting circuit having a first input configured to receive an digital input signal and a first output configured to output a digital level shifted signal, said level shifter connected between a first positive supply voltage and a second negative supply voltage;
- and
- an amplifier circuit having a second input configured to receive the digital level shifted signal and a second output configured to output a digital output signal, said amplifier circuit having a gain between second input and second output and said amplifier circuit connected between a second positive supply voltage and a second negative supply voltage;
- wherein the first positive supply voltage substantially equals the second positive supply voltage divided by the gain;
- and
- wherein the first negative supply voltage substantially equals the second negative supply voltage divided by the gain.
3 more elements
Dependencies are inferred from the claim text.