Infinite impulse response filter architecture with idle-tone reduction

摘要

A digital infinite impulse response filter has a plurality of cascaded filter elements, with each filter element defining a pole of the filter and wherein the poles lie inside a unit circle. The filter elements are configured such that the p of the last filter element is a real number. In one embodiment the poles are arranged as complex conjugate pairs. In another embodiment the real part of the output of each filter element is extracted before being passed to the next filter element. This architecture offers improved idle tone with reduced complexity.

主权项

1. A digital infinite impulse response filter, comprising:
a plurality of cascaded filter elements, each filter element defining a pole of the filter and having an input and an output, and wherein the poles lie inside a unit circle; a string of cascaded delay lines downstream of the filter elements; and a summer for summing the outputs of the delay lines to provide an output signal of the infinite impulse response filter, wherein the filter elements are configured such that the output of the last filter element is a real number.