Noise shaping for digital pulse-width modulators

A circuit comprising:

• an analog-to-digital converter (ADC) configured to receive an analog feedback signal and an analog input signal and generate a digital output;
• a noise shaper configured to truncate the digital output, and to shape quantization noise of the digital output based on a Z-domain transfer function selected from a group consisting of
• z
• -
• 1
• 1
• -
• z
• -
• 1
• and
• 1
• 1
• -
• z
• -
• 1
• ;
• and
• a pulse width modulation digital-to-analog converter (PWM DAC) configured to process the digital output of the noise shaper output and generate a PWM DAC output.

A method of reducing quantization noise using a pulse width modulator, the method comprising:

• converting an analog input signal to a digital signal using a sigma delta analog-to-digital converter (ΣΔ ADC);
• summing the digital signal with a feedback digital signal;
• integrating the summed digital signal for a duration;
• truncating the digital signal using a noise shaper;
• outputting the truncated digital signal as the feedback digital signal and an output digital signal;
• and
• converting the output digital signal to an output analog signal,
• wherein the summing, the integrating, and the truncating collectively shift a quantization error to a frequency above a clock rate of the noise shaper.