Analysis of the High-frequency Harmonic Characteristics of the ladder wave based on timed sampling

A signal after A/D sample and hold will form the ladder wave with the sampling frequency, and the high-frequency harmonics of the ladder wave will inevitably affect the features of the digital control system and other devices connected to the same distribution power grid. This paper accurately analyzes the high-frequency harmonic characteristics of a sine ladder wave based on timed sampling through mathematical modeling. The theoretical analysis and simulation results show that, for the sine ladder wave, the high-frequency harmonics mainly distribute at the two frequency points centered on the integer multiple sampling frequencies, and the amplitude of the difference frequency harmonic between the integer multiple sampling frequencies and the fundamental frequency is greater than that of the sum frequency harmonic. Furthermore, for the ladder waves formed from arbitrary signals, the high-frequency harmonics are expanded successively around the integer multiple sampling frequencies. The number of the high-frequency harmonics depends on the low-frequency harmonics of the original signal, and the higher the harmonic order of the low-frequency original harmonics, the larger the amplitude of the high-frequency harmonics.