Performance analysis of multi-rate signal processing digital filters on FPGA

Qingfeng Jing,Yujia Li,Jincheng Tong

doi:10.1186/s13638-019-1349-9

Abstract

Multi-rate signal processing, an important part of the design of a digital frequency converter, is realized mainly based on interpolation and decimation, which match the sampling rate between the baseband and high-frequency processing side, especially in down conversion. However, the design of a digital filter is important for realizing multi-rate interpolation and decimation, which is highlighted in this paper. To analyze the digital filter performance in multi-rate signal processing, the ordinary finite impulse response (FIR) filter and more efficient digital filter are discussed respectively. The ordinary FIR filters use a Hamming window to design, while a more efficient digital filter includes a cascaded integrate comb (CIC) and half-band filter. Sampling rate transformation factor is 12 in this design, which is cascaded by three stages. Each stage corresponding to the conversion factor is 3, 2, and 2. Both of these design methods are implemented on the FPGA development board. The hardware resource occupancy and the error rate of the signal amplitude in decimation show that the efficient digital filter is superior to the digital filter designed by the Hamming window in the real-time processing.

Highlights

Multi-rate signal processing is the key technology to realize the digital frequency converter
In a general communication system, the rate of the baseband signal is often much lower than that of the intermediate frequency (IF) signal; in order to match the sampling rate of both sides, there is no doubt that the sampling rate of the former increases, which is equivalent to the increase in the number of sampling points
Analog frequency conversion aims at moving high-frequency analog signal to the appropriate IF, which can reduce the restrictions of key devices such as AD/DA, and digital frequency conversion is prone to get a lower rate baseband signal [3]

Summary

Introduction

Multi-rate signal processing is the key technology to realize the digital frequency converter. Traditional analog circuits cannot meet the whole design demands Those large-scale integrated devices, such as FPGA and DSP as high-speed signal processors, have been vigorously developed and promoted, which is characterized by the use of digital or software to replace the analog circuit [2]. Most of the transceivers include baseband signal processing, digital frequency conversion, and analog conversion. Analog frequency conversion aims at moving high-frequency analog signal to the appropriate IF, which can reduce the restrictions of key devices such as AD/DA, and digital frequency conversion is prone to get a lower rate baseband signal [3].

Methods

Half-band filter

Implementation of two multi-rate digital filter designs

Results and discussion