| 摘要 |
A parallel IIR filter (100) has low quantization effects and includes a multiplier (103) which multiplies a digital input signal by a constant, and an arbitrary number of biquad filters (104, 105). Outputs of the multiplier (103) and each biquad filter (104, 105) are summed together in a summing device (106) to provide an output signal of the IIR filter (100). The IIR filter (100) first expresses its transfer function as a cascade form transfer function, and then calculates the constant as a product of a constant term of each cascade form biquad term. The IIR filter (100) partially decomposes the cascade form transfer function to provide first order terms, and calculates numerator coefficients of the first-order terms. Pairs of decomposed terms are recombined to provide a parallel form transfer function, from which parallel form coefficients are taken and applied to the biquad filters (104, 105).
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