Nanometer time grating makes measurement with moving reference frame constructed by alternating elec⁃tric field. Precision of the excitation directly affects the uniform motion of the reference frame,and thus influences the accuracy of measurement. In order to meet the requirement of high precision excitation,a new signal source adopting closed loop control was designed. FPGA was used to complete overall control,including acquisition con⁃trol,data processing and waveform data generating. Signal generating circuit and feedback circuit were constructed with 16-bit D/A and A/D converters,therefore the precise control of signals was improved a lot. The test results show that the precision of the signal amplitude is 0.01%and the phase precision is 0.1%,and the original precision of nanometer time grating was improved from 1.4μm to 0.9μm.%纳米时栅利用正交变化电场构建的运动参考系进行测量，激励信号精度直接影响运动参考系匀速性，进而影响测量精度。针对纳米时栅需要高精度激励信号的要求，设计了一种采用闭环控制结构的高精度激励信号源，该信号源采用单片FPGA实现总体控制，完成采集控制、数据处理和波形数据产生等功能，利用16位高精度数据转换器构建信号发生电路及反馈电路，保证了对信号的精确控制。测试结果表明：输出正弦信号幅值精度为0.01%，相位精度为0.1%，并将纳米时栅原始精度从1.4μm提高至0.9μm。
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