Abstract:
A digital class D amplifier (10) is disclosed, comprising a pulse width modulator (PW Mod) comprising: a digital loop filter (Loop F) adapted to receive an input signal (x[n]) and a feedback signal (fb[n]), the digital loop filter (Loop_F) being adapted to process at a clock frequency (f_s) said input and feedback signals for providing as output a filtered digital signal (w[n]); a PWM conversion module (PW_CM) having an input (24) for receiving the filtered digital signal (w[n]) and having a first output (25) connected to the digital loop filter (Loop F), the PWM conversion module being adapted for processing the filtered digital signal (w[n]) and providing at said first output (25) the feedback signal (fb[n]). The PWM conversion module (PW_CM) comprises: a first comparator (CMP_N) adapted to compare the filtered digital signal (w[n]) with a first reference triangular waveform (VTn[n]) for providing as output a first PWM signal (yn[n]), the first reference triangular waveform having a frequency (f_osc) much lower than said clock frequency (f.s); a second comparator (CMP_P) adapted to compare the filtered digital signal (w[n]) with a second reference triangular waveform (VTp[n]) for providing as output a second PWM signal (yp[n]), the second reference triangular waveform (VTp[n]) being the inverse of the first triangular waveform (VTn[n]), said first (yn[n]) and second (yp[n]) PWM signals representing a differential output pulse width modulated signal (yn[n],yp[n]).
Abstract:
A digital class D amplifier (10) is disclosed, comprising a pulse width modulator (PW Mod) comprising: a digital loop filter (Loop F) adapted to receive an input signal (x[n]) and a feedback signal (fb[n]), the digital loop filter (Loop_F) being adapted to process at a clock frequency (f_s) said input and feedback signals for providing as output a filtered digital signal (w[n]); a PWM conversion module (PW_CM) having an input (24) for receiving the filtered digital signal (w[n]) and having a first output (25) connected to the digital loop filter (Loop F), the PWM conversion module being adapted for processing the filtered digital signal (w[n]) and providing at said first output (25) the feedback signal (fb[n]). The PWM conversion module (PW_CM) comprises: a first comparator (CMP_N) adapted to compare the filtered digital signal (w[n]) with a first reference triangular waveform (VTn[n]) for providing as output a first PWM signal (yn[n]), the first reference triangular waveform having a frequency (f_osc) much lower than said clock frequency (f.s); a second comparator (CMP_P) adapted to compare the filtered digital signal (w[n]) with a second reference triangular waveform (VTp[n]) for providing as output a second PWM signal (yp[n]), the second reference triangular waveform (VTp[n]) being the inverse of the first triangular waveform (VTn[n]), said first (yn[n]) and second (yp[n]) PWM signals representing a differential output pulse width modulated signal (yn[n],yp[n]).