带有小数补偿的低频数控振荡器及其基于FPGA的实现

在分析数控振荡器（NCO）工作原理的基础上，以低频信号为例，研究了影响NCO性能的几个因素。结合杂散特性，着重讨论了频率控制字误差对输出频率带来的影响，提出在相位累加器中加入小数部分补偿，以使降低信号频率门限值和提高输出的准确性。最后采用FPGA（现场可编程门阵列）实现了带有小数补偿的NCO，在兼顾硬件资源的同时优化了系统性能，另外通过仿真验证了这种方法的可行性。

Low-frequency numerically controlled oscillator with decimal compensation and realization with FPGA

By taking low frequency signal as example, several factors of affecting the performance of the NCO （numerically controlled oscillator） are studied on the basis of analysing the principle of NCO. The influence of frequency control word error on the output frequency is discussed emphatically in the light of spurious characteristic, and it is presented to add the decimal compensation in the phase accumulator for reducing the threshold and improving the accuracy of the output signal. Finally an NCO with decimal compensation has been realized based on FPGA（field programmable gate array）, which not only takes account of the hardware source, but also optimizes the system performance. The simulation has verified the feasibility of this method.