Cascaded integrator-comb filter as a non-integer sample rate converter

摘要

The implementation of non-integer sample rate conversion and filtering of data sequences may be improved by performing both operations together with a system that includes a CIC filter and a control block that modifies internal states of the CIC filter. In one embodiment, input data samples provided at a first sample rate may be filtered by a CIC filter that includes a cascade of an integrating stage and a comb filter stage, each stage operating at a different sampling rate. A control block coupled to the CIC filter may modify at least one internal state of at least one of the integrating stage and comb filter stage of the CIC filter, wherein filtering by the CIC filter and modifying the at least one internal state causes the CIC filter to output data samples at a second sample rate unequal to the first sample rate.

主权项

1. An apparatus, comprising:
a cascaded integrator-comb (CIC) filter comprising a cascade of an integrating stage and a comb filter stage, each stage operating at a different sampling rate, wherein the CIC filter is configured to filter input data samples provided at a first sample rate; and a control block coupled to the CIC filter, wherein the control block is configured to modify at least one internal state of at least one of the integrating stage and the comb filter stage of the CIC filter, wherein the control block is further configured to perform the steps of:
calculating the first sampling rate; anddetermining a timing offset between the first sampling rate and a ratio of the second sampling rate based, at least in part, on the calculated first sampling rate, and wherein the CIC filter is further configured to, in response to modification by the control block and filtering of the input data samples, output data samples at a second sample rate unequal to the first sample rate.