Abstract: A technique for correcting higher order delta sigma modulators in audio components, which use mutually nonlinear feedback and feed forward functions. Methods and apparatus are provided to correct jitter and spread in the delta sigma converter due to quantization error, to permit the processing of data streams entering the converter at a different clock rate from that of the modulator, and to permit step up ratios to be changed on the fly in order to reduce radio frequency interference from the output signal.

Abstract: Circuitry is provided to compensate for distortion introduced into the output signal of a delta sigma digital to analog converter (DAC) by the power output stage of the amplifier. Such distortion is not consistent for a given output data value or short series of data values, but must be either measured and corrected in real time or must be corrected in real time based upon a sophisticated model of the system that predicts the distortion. Correction is applied to one or more feedback loops in the delta sigma converter. Distortion caused by fluctuations in the power supply voltage may also be modeled and corrected in real time.

Abstract: A multibit data converter has an output parallel unit element converter fed by a multibit signal, and noise shaping dynamic element matching (DEM) apparatus for selectively activating units in the converter. The DEM apparatus includes a plurality of noise shaping components. Each components has as an input one signal to the converter, and each includes a first integrator having as its input the input to the component, and a second integrator having as its input the output of the first integrator, and forms one or more component outputs. A signal in the second integrator is clipped. A vector quantizer orders the component outputs and activates converter elements according to the ordering.

Abstract: Distortion and noise in high power digital PWM amplifiers is reduced by measuring the difference between the desired output signal and the actual output signal on a pulse by pulse basis. This analog error is converted into a digital signal with an analog to digital converter (ADC). The digital error signal is then used to correct the feedback of the delta sigma modulator in real time. Preferably, more than one moment of the modulator signal is corrected via the feedback. Preferably, the predictable error of the circuitry which is known a priori is also corrected by correcting the delta sigma modulator feedback. A specialized ADC allows the loop delay to be low, without compromising accuracy.