Research On Multi-channel Arbitrary Waveform Generator With High-precision Phase Control

Along with the rapid development in the fields of science and technology and production in our country, it has put forward higher requirements in the corresponding test equipment and test method, and it usually needs some special waveform signal to study the system characteristics. In addition, it also needs more even dozens of channels of waveform signal with high precision phase difference in the process of precision measurement and equipment debugging. At present, our country for the study of the arbitrary waveform generator has made certain achievements, but there are many problems in extension of the output channel and precision phase control, so it urgently needs one multi-channel AWG, which has an expanded channel and high precision phase control.According to the above problems, this paper designs one kind of multi-channel AWG with high precision phase control, and it uses DDS technology based on FPGA to realize the generation of arbitrary waveform, and uses the closed-loop real-time compensation of phase to achieve the precise phase control, and also it gets multiple systems work in parallel through external clock synchronization trigger modules to expand output channels.This paper has carried on the overall scheme design for the multi-channel waveform generator, it takes the ARM as the core, uses FPGA to realize the direct digital frequency synthesis(DDS) technology, through the D/A conversion, low-pass filter, and amplitude modulation circuit to generate arbitrary waveform, and the experimental results show that the quality of the output of arbitrary waveform is better. Based on the high-speed A/D sampling technology, this paper puts forward a method of the closed-loop real-time phase control, which makes high-speed sampling of the output waveform and deals with the sampled data with DFT algorithm to measure the phase difference in the ARM, and uses the incremental PID control algorithm to adjust the phase control word in real-time, until the sampled phase is equal to the output phase control word, the experiments show that this method can achieve high precision phase control. Based on trigger synchronization technology, this paper puts forward a design of external clock synchronization trigger input module, which realizes the high precision synchronization among the output systems, and the experimental results show that the method can achieve multiple systems work in parallel, expand the output channels, and the phase relationship of the output waveform has high precision. In this article, through transplanting the file operation system of Fatfs and writing the GUI interface graphics library, it better realizes the management of arbitrary waveform, friendly human-computer interaction interface, and makes the system convenient for users to operate, improving the system human-computer interaction.The system experimental results show that the system’s phase accuracy control is within ±0.02°, achieving high precision phase control, and can realize the parallel output among systems, expand output channels, and can generate different kinds of conventional waveform and arbitrary waveform defined by users, the frequency resolution of which reaches 1μHz, and adjustable amplitude range is 1m Vpp ~ 10.000 Vpp, and all the parameters meet the requirements of performance indicators, thus this system is stable, reliable and it has advantages such as high operability, good flexibility and low cost, and it has great application value for test and measurement and equipment debugging with high precision.