An apparatus (100) comprises a signal generator (101) that is set up to produce a digital random signal (191). The apparatus (100) also comprises at least one filter element (102, 121, 122) that is set up to apply a high pass filter and a low pass filter to the digital random signal (191) in order to produce a spectrally shaped random signal (112). The apparatus (100) also comprises a modulator (103) that is set up to apply the spectrally shaped random signal (192) as dither.

A noise shaping circuit according to an example includes a forward signal path configured to generate an output signal based on an input signal, a feedback signal path configured to feed back a feedback signal based on the output signal to the forward signal path, and a dither generator configured to generate a dither signal and to couple the dither signal into the forward signal path to modify the input signal and into the feedback signal path. Employing a noise shaping circuit according to an example may improve an overall noise performance.

A sigma-delta analog to digital converter (ADC) includes an M-bit digital-to-analog converter (DAC); a loop filter coupled to receive an output from DAC; and a variable level quantizer configured to provide a uniform quantization function by switching between an N-level quantizer function and an N1 level quantizer function.