摘要
讨论了定点IIR滤波器在CSR8670平台上的高精度实现问题。定点DSP芯片由于低成本和低功耗等原因被广泛应用于消费类电子产品。IIR滤波器作为基本的信号处理模块,被广泛应用于各类数字信号处理芯片中。然而由于定点芯片字长有限,导致定点IIR滤波器的运算精度严重下降。本文从零极点分布及幅频响应的角度分析了定点IIR滤波器实现过程中存在的问题。为提高运算精度,提出一种双精度乘法,即利用24位乘法器实现48×48位乘法运算,仿真实验表明该方法可将计算精度提高4个数量级。
The problem of realization of high precision fixed-point IIR filter based on CSR8670 chip is discussed. Fixed-point DSP chips have been extensively used in consumer electronics products because of their low cost and low power consumption. IIR filter is widely used in various DSP chips as a fundamental signal processing module. However, the computation precision of fixed-point IIR filter decreases badly because of the limited word length of chips. The problem of decreased precision of fixed-point IIR filter is analyzed in terms of pole-zero positions and the amplitude frequency response. To improve the computation precision, this paper presents a double-precision method that 48×48-bit multiplication is realized with 24-bit multipliers, and experiments verify that the computation precision is improved by four orders of magnitude with the proposed method.
引文
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