Sigma-delta analog-digital converter for an xdsl multistandard input stage

Abstract

The invention relates to a sigma-delta analogue/digital converter for an xDSL multi-standard input stage for converting an xDSL signal into a digital output signal, where the sigma-delta analogue/digital converter () has: an analogue loop filter () which filters an analogue difference signal between the xDSL signal to be converted and a feedback signal in order to produce a filter output signal; a quantizer which quantizes the filter output signal from the analogue loop filter () in order to produce the digital output signal; a first digital/analogue converter () which converts the digital output signal into the analogue feedback signal; where the analogue loop filter () has at least two resonator filter stages () which respectively comprise a first integrator (--) and a second integrator (--) connected in series therewith, where the second integrator (--) can be connected to the first integrator (--) by means of a controllable feedback switch (--) in order to close a local feedback loop, where the integrator outputs can respectively be connected by means of a controllable switch () to a signal input of an adder () which adds the output signals from the integrators in order to produce the filter output signal.