Signal conversion system and method
AssigneeActiwave AB
InventorsErik Lindahl, Pär Gunnars Risberg
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Abstract
A signal conversion system and method for converting an input signal to a pulse width modulated signal is disclosed. The signal conversion system includes a sample rate converter coupled with an associated pulse width modulation (PWM) module. A hardware and power efficient signal conversion system for resampling an audio input signal with an arbitrary sample rate to a pulse width modulated output audio signal for use in an audio processor and/or reproduction is disclosed. The signal conversion system may be particularly suitable for use in a battery operated consumer electronics device.
Claims24
A signal conversion system for converting an input signal to a pulse width modulated (PWM) output signal comprising:
- a clock source for generating and/or for accepting a clock signal;
- a carrier generator configured to generate a carrier signal with a carrier signal frequency;
- a cross-point section (CPS) block comprising a CPS comparator to compare the carrier signal to the input signal or a signal derived therefrom to produce a triggered signal based on the comparison and the input signal or the signal derived therefrom;
- a noise shaper configured to bit depth reduce the triggered signal to form a truncated signal;
- a PWM comparator configured to compare the truncated signal and/or a signal generated therefrom with the carrier signal to produce the PWM output signal;
- and
- a sample rate converter comprising a counter configured to generate a count-disparity signal from the clock signal and the input signal, a first sigma delta unit configure to calculate a temporal correction value from the count disparity signal, a resampled clock generator configured to generate one or more resampled clock signals from the temporal correction value, and a second sigma delta unit configured to generate the resampled signal from one or more of the resampled clock signals and the input signal.
A signal conversion system for converting an input signal to a pulse width modulated (PWM) signal comprising:
- a clock source for generating and/or for accepting a clock signal;
- a cross enable unit configured to generate one or more resampled clock signals and a de-jittered signal from the input signal and the clock signal;
- a linear interpolation unit configured to generate a resampled signal from the de-jittered signal, the clock signal, and one or more of the resampled clock signals;
- and
- a pulse width modulation (PWM) module comprising a carrier generator to generate a carrier signal, and a PWM comparator configured to compare the resampled signal or a signal derived therefrom and the carrier signal to form the PWM signal.
A method for generating a pulse width modulated (PWM) signal from an input signal and a clock signal both with respective sample rates comprising:
- calculating a count disparity signal from the input signal and the clock signal, the count disparity signal relating to the difference in sampling rate between the clock signal and the input signal;
- generating a temporal correction signal from the count-disparity signal, the temporal correction signal corresponding to a new sample rate, different from the input signal sample rate or the clock signal sample rate;
- interpolating the input signal at the new sample rate to form a resampled signal;
- forming a carrier signal with an initial value;
- and
- comparing the resampled signal or a signal generated therefrom with the carrier signal to form the PWM signal.
Dependencies are inferred from the claim text.