| 摘要 |
An active noise reducing device includes processing circuit (101) which includes sine wave generator (102) for generating a sine wave having a specific frequency, cosine wave generator (103) for generating a cosine wave having the same frequency as that of the sine wave, and two one-tap digital filters (104), (105) for processing the outputs from generators (102), (103). The processing circuit (101) also has two coefficient updating sections (106) and (107), which output a sum of outputs from digital filters (104) and (105). Updating sections (106) and (107) update respective coefficients of filters (104), (105) based on a sum of this output from updating sections (106) and (107) and respective inputs to updating sections (106) and (107), and the respective outputs from generators (102), (103). The noise reducing device also has adjusting circuit (108) for adjusting the phase and amplitude of an output from processing circuit (101), adjusting circuit (108) 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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