Power efficiency in an analog feedback class D modulator
AssigneeAnalog Devices International Unlimited Company
InventorsAbhishek Bandyopadhyay, Atsushi Matamura
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Abstract
Systems and methods are provided for architectures for an analog feedback class D modulator that increase the power efficiency of the class D modulator. In particular, systems and methods are provided for an analog feedback class D modulator having a digital feed-forward loop. The digital feed-forward loop allows for removal of signal content from an input to an analog-to-digital converter, such that the ADC processes just noise and/or error. Using the techniques discussed herein, the loop filter is low power as it processes error content but not signal content.
Claims20
An architecture for a class D modulator, comprising:
- a digital input line configured to receive a digital input signal, wherein the digital input line is split into a first parallel line and a second parallel line;
- a digital-to-analog converter coupled to the first parallel line, the digital-to-analog converter configured to receive the digital input signal and convert the digital input signal to an analog input signal;
- an analog summer configured to subtract an analog feedback signal from the analog input signal and generate an analog summer output;
- a loop filter configured to receive the analog summer output and produce a filtered analog output;
- a quantizer configured to quantize the filtered analog output and output a quantized signal;
- a filter module coupled to the second parallel line configured to digitally filter the digital input signal generating a filtered digital input signal, wherein the filtered digital input signal is fed forward;
- and
- a digital summer configured to add the filtered digital input signal to the quantized signal generating a digital modulator output signal.
An architecture for a class D modulator, comprising:
- a digital input line configured to receive a digital input signal, wherein the digital input line is split into a first parallel line and a second parallel line;
- a first digital-to-analog converter (DAC) coupled to the first parallel line, the first DAC configured to receive the digital input signal and convert the digital input signal to an analog input signal;
- a first analog summer configured to subtract an analog feedback signal from the analog input signal and generate a first analog summer output;
- a loop filter configured to receive the first analog summer output and produce a filtered analog output;
- a signal processing module coupled to the second parallel line, the signal processing module configured to receive the digital input signal and a quantized signal and generate a processed signal;
- a second digital-to-analog converter (DAC) configured to convert the processed signal to an analog processed signal;
- a second analog summer configured to add the analog processed signal to the filtered analog output;
- and
- a quantizer configured to quantize a second summer output and generate the quantized signal.
A method for an analog class D modulator, comprising:
- receiving a digital input signal at a digital input including a first parallel line and a second parallel line;
- in the first parallel line:
- converting the digital input signal to an analog input signal at a first digital-to-analog converter (DAC);
- filtering the analog input signal at a loop filter to generate a filtered signal;
- and
- quantizing the filtered signal to generate a quantized signal;
- in the second parallel line:
- filtering the digital input signal to generate a filtered digital input signal;
- and
- adding the filtered digital input signal to the quantized signal to generate a digital modulator output signal.
Dependencies are inferred from the claim text.