Abstract: The invention provides an apparatus and a method for performing a calculation operation with at least one input signal consisting of signal sections, wherein each signal section of said input signal has a constant amplitude. The apparatus comprises a signal transformation unit for transforming at least one input signal into a first intermediary signal having a virtual amplitude with respect to at least one carrier signal. The calculation unit is provided for performing the calculation operation on said first intermediary signal to generate a second intermediary signal. A signal re-transformation unit re-transforms the second intermediary signal into an output signal consisting of signal sections, wherein each signal section of said output signal has a constant amplitude.

Abstract: The invention provides an apparatus and a method for performing a calculation operation with at least one input signal consisting of signal sections, wherein each signal section of said input signal has a constant amplitude. The apparatus comprises a signal transformation unit for transforming at least one input signal into a first intermediary signal having a virtual amplitude with respect to at least one carrier signal. The calculation unit is provided for performing the calculation operation on said first intermediary signal to generate a second intermediary signal. A signal re-transformation unit re-transforms the second intermediary signal into an output signal consisting of signal sections, wherein each signal section of said output signal has a constant amplitude.

Abstract: A noise shaper for shaping a power spectral density of an input signal which consists of signal intervals, wherein each signal interval has a corresponding signal amplitude being constant for a variable interval duration time of the signal interval, said noise shaper comprising a calculation unit having at least one serial connected integrator wherein each integrator calculates an integrated signal of different order from said input signal, and a weighting unit for weighting each integrated signal with a corresponding adjustable weighting coefficient according to a noise transfer function.

Abstract: Switching power amplifier includes a first signal path having a pulse modulator for modulating an input signal, and a switching power unit for amplifying the modulated signal to generate an amplified output signal; a second signal path for generating a reference signal in response to the input signal; and a sigma delta feedback loop having a substractor for substracting the generated reference signal from the amplified input signal to generate an error signal, an analogue noise shaper for integrating the error signal to generate an integrated error signal, and a quantizer for converting the integrated error signal into a digital feedback signal which is fed back to the first signal path.