Noise shaping for digital pulse-width modulators
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsEric Soenen, Alan Roth, Martin Kinyua, Justin Shi, Justin Gaither
Life of this patent
Estimating the term…
Abstract
A noise shaper that compares an input signal to a feedback output signal, which is a truncated version of the input signal, and generates the difference between the two signals (i.e., the error). The noise shaper then integrates the errors by adding to the error multiple of its delayed versions, and quantizes the integrated errors in such a way that the spectrum of the quantization noise is shaped toward high frequencies to be removed by a LC low-pass filter used in conjunction with the noise shaper. The low frequency content of the desired signal is mostly unaffected.
Claims20
A circuit comprising:
- an ADC configured to receive an analog feedback signal and an analog input signal and generate a digital ADC output;
- a digital filter configured to control a frequency response of the digital ADC output and generate a digital filter output having a first number of bits;
- a noise shaper configured to truncate the first number of bits and generate a noise shaper output having a second number of bits that is less than the first number of bits, and to shape quantization noise generated during truncation;
- and
- a PWM DAC configured to process the second number of bits of the noise shaper output and generate a PWM DAC output.
A circuit comprising:
- an ADC configured to receive an analog feedback signal and an analog input signal, and generate a digital ADC output;
- a digital filter configured to control a frequency response of the digital ADC output and generate a digital filter output Vin;
- a noise shaper configured to process Vin and generate a noise shaper output Vout based on an equation is selected from a group consisting of
- Vout
- =
- Vin
-
-
- z
- -
- n
-
-
- 1
- +
- Vq
-
- (
- 1
- -
- z
- -
- 1
- )
- n
-
-
- 2
- and
- Vout
- =
- Vin
- +
- (
- 1
- -
- z
- -
- 1
- )
- n
-
-
- 2
-
- Vq
- wherein Vq represents quantization noise generated in the circuit, z represents a time delay, n1 represents a number of delays experienced by Vin, and n2 represents an order of the noise shaper;
- a PWM DAC configured to process the noise shaper output and generate a PWM DAC output;
- and
- a low pass filter configured to remove high frequencies associated with Vq;
- an output of the low pass filter including the analog feedback signal.
A circuit comprising:
- an ADC configured to receive an analog feedback signal and generate a digital ADC output;
- a digital filter configured to control a frequency response of the digital ADC output and generate a digital filter output;
- a noise shaper configured to process the digital filter output and generate a noise shaper output;
- a PWM DAC configured to process the noise shaper output and generate a PWM DAC output;
- a switching stage configured to process the PWM DAC output and generate a switching stage output;
- and
- a low pass filter configured to filter high frequency quantization noise shaped by the noise shaper, and generate the feedback analog signal.
Dependencies are inferred from the claim text.