| 摘要 |
DC transients are removed from a digital filter such as a sigma delta filter (in particular from a sigma delta high pass filter) from the outset by presetting an input summing node to a sigma delta modulator. While the input summing node may be preset using any appropriate input, in a disclosed embodiment, a sigma delta high pass filter is preset by switching a partial feedback term between an input containing the non-zero preset value and the normal input comprising the output from the input summing node. The preset value is chosen based on the value of the zero of the transfer function of the sigma delta high pass filter, e.g., with the complement of the gain factor.
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