Sample rate converter, an analog to digital converter including a sample rate converter and a method of converting a data stream from one data rate to another data rate

Abstract

It is known to perform sample rate conversion. A sample rate converter is arranged to receive digital data at an input sample rate Fand to output data at an output sample rate F, where F=F/N, and N is decimation factor greater than 1. A problem can arise with sample rate converters when a user wishes to change the decimation rate. Generally a sample rate converter needs to discard the samples in its filter when the decimation rate is changed, and the filter output is unusable until the filter has refilled with values taken at the new decimation rate. The sample rate converter provided here does not suffer from this problem. The sample rate converter includes at least Q channels. Each channel comprises a Qth order filter arranged to select input signals at predetermined intervals from a run of P input signals, and to form a weighted sum of the selected input signals to generate an output value, and where the runs of P input signals of one channel are offset from the runs of P signals of the other channels.