The invention relates to a converter as described in the preamble of claim 1. Converters comprising a D/A converter and a low pass filter are known in the art. For example oversampled converters are used in audio reproduction systems in combination with a digital upsampling low pass filter followed by either an analog time continuous or a time discrete low pas filter which is needed to remove the remaining high frequency content of the output signal. The sampling frequencies of the input data of the converter and of the time discrete low pas filter are mostly equal or have a fixed ratio. In systems using noise shaping converters of the delta sigma type, which is also a proposed format for SACD players, the initial signal band width can be very high but a large amount of high frequency noise is generated in the delta sigma conversion, which sometimes can overload the connected audio equipment. In which case the bandwidth of the output signal has to be reduced.
It is inter alia on object of the invention to provide a converter, which overcomes the drawbacks of the prior art. To this end a converter according to the invention comprises the features as claimed in claim 1. In this way it is possible to amend the bandwidth of the output signal depending on the noise by changing the ratio of sampling frequencies of the noise shaped D/A input data and of the (time discrete) low pass filter.
Embodiments of the invention are described in the dependent Claims.
USPTO Backgrounds
USPTO Backgrounds