基于PCIe的高精度低杂散信号源设计

Design of High Precision Low Spurious Signal Source Based on PCIe

为了在动态压力测试系统中提供1种精度高、便携式与可靠性强的信号源以完成校准测试工作,通过采用现场可编程门阵列(FPGA)芯片作为控制核心,设计了1种高精度、低杂散的信号源。基于直接数字式频率合成器(DDS)基本原理,利用高速串行计算机扩展总线(PCIe)标准发送上位机指令及大量波形数据,通过16位的4通道模数转换芯片DAC8544输出各类型信号。采用Xilinx提供的DDS Compiler知识产权(IP)核与Block Memory Generator知识产权(IP)核实现任意信号及调制信号的输出,以减少设计电路体积。此外,提出引用有限长单位冲激响应(FIR)滤波器插值滤波与相位抖动技术,对输出杂散进行了处理。试验结果表明,信号源频率范围为10 Hz~10 MHz,幅值±5 V可调,无杂散动态范围优于60 dB,频率误差在0.05%以内。该信号源输出信号精度高、杂散低,具有实际的应用价值,也可用于航空发动机、汽轮机等其他动态测试领域。

To provide a highly accurate, portable and reliable signal source for calibration testing in dynamic stress test systems, a high precision and low spurious signal source is designed by using field programmable gate array(FPGA) chip as the control core. Based on the basic principle of direct digital synthesis(DDS), peripheral component interconnect express(PCIe) standard is used to send host computer commands and a large amount of waveform data to the DAC8544, a 16-bit, four-channel analogue-to-digital converter chip, to output various types of signals. The DDS Compiler intellectual property(IP) core and the Block Memory Generator IP core provided by Xilinx are used to output arbitrary and modulated signals, reducing the size of the design circuit. In addition, finite impulse response(FIR) filter interpolation filtering and phase dithering techniques are proposed to deal with the output spurious. Tests have shown that the signal source has a frequency range of 10 Hz to 10 MHz, an amplitude of ±5 V adjustable, a spurious-free dynamic range of better than 60 dB and a frequency error of 0.05% or less. The signal source has high output signal precision and low spurious, which has practical application value and can also be used in other dynamic testing fields such as aero-engine and steam turbine.