Decimation filter for oversampling analog-to digital converter

Abstract

The disclosure is generally directed to an improved structure for a decimation filter. More specifically, the disclosure includes a method and apparatus for decimating an oversampled signal at the input, which is the output of an oversampling analog-to-digital converter. In accordance with one aspect of the system, an apparatus is provided for decimating an oversampled signal. The apparatus includes at least one non-recursive decimator. Specifically, the at least one non-recursive decimator is configured to receive the oversampled input signal defined by a first sampling frequency. This at least one non-recursive decimator is further configured to generate a output having a second sampling frequency. The apparatus further includes a recursive decimator. The recursive decimator is configured to receive the output of the at least one non-recursive decimator and generate an output having third sampling frequency. It will be appreciated that the second sampling frequency output from the non-recursive decimator is less than the sampling frequency of the oversampled input signal, and further that the third sampling frequency is less that the second sampling frequency. In accordance with another aspect of the disclosure, a method is provided for decimating an oversampled signal. Broadly, the method includes the steps of decimating the oversampled signal in accordance with a non-recursive decimation algorithm to generate an interim decimated signal, and decimating the interim decimated signal in accordance with a recursive decimation algorithm to generate a final decimated signal.