| 摘要 |
An active noise reducing device includes processing circuit includes a sine wave generator for generating a sine wave having a specific frequency, a cosine wave generator for generating a cosine wave having the same frequency as that of the sine wave, and two one-tap digital filters for processing the outputs from the generators. The processing circuit also has two coefficient updating sections, which output a sum of outputs from the digital filters. Updating sections update respective coefficients of the filters based on a sum of this output from the updating sections and respective inputs to the updating sections, and the respective outputs from the generators. The noise reducing device also has an adjusting circuit for adjusting the phase and amplitude of an output from the processing circuit, the adjusting circuit thus generates a control signal of opposite phase and equal in amplitude to original noise, so that random noise such as load noise can be reduced.
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