Square wave signal generator

Abstract

The present invention discloses a square wave signal generator. The square wave signal generator includes a direct digital synthesizer (DDS) module, a wave shape selecting unit and a comparator. The DDS module is connected with the wave shape selecting unit. The wave shape selecting unit is connected with the comparator. At low frequency and high frequency, the square wave signal generator separately selects different initial signals as initial wave shapes. At low frequency, a fast pulse signal is selected, and at high frequency, a basic wave shape signal is selected. Level comparison and shaping are performed by using a comparator circuit, so that a low frequency square wave that is faster, jitters lower, and has a fine and adjustable duty cycle is obtained, and a high frequency square wave that is faster and jitters lower is obtained. The square wave signal generator has the advantages of the fast pulse signal and the comparator circuit.

Description

technical field [0001] The present application relates to the field of electronic instruments, in particular to a square wave signal generator. Background technique [0002] DDS (Direct Digital Synthesizer) is a direct digital frequency synthesizer that can generate basic waveform signals. At present, there are two traditional methods for generating square wave signals: one is a comparator circuit built with discrete components, and the basic waveform generated by DDS The waveform signal is compared and shaped to obtain a square wave signal; the other is to fill the corresponding square wave data into the waveform data memory according to different needs, and then directly output the square wave signal in the form of DDS. The disadvantage of the first type is that the signal jitter is large, the trigger position is unstable, the adjustable range of the edge is small and the adjustment is difficult, and the duty cycle adjustment accuracy is small. Another disadvantage is tha...

AI Technical Summary

Problems solved by technology

The disadvantage of the first type is that the signal jitter is large, the trigger position is unstable, the adjustable range of the edge is small and the adjustment is difficult, and the duty cycle adjustment accuracy is small

Another disadvantage is that the size of the edge is affected by the frequency of the square wave signal. The edge time is very large (millisecond level) at low frequencies, and fast edges (nanosecond level) cannot be set, and the duty cycle of the low frequency signal is minimum. It is limited and cannot be finely adjusted; if a low-frequency square wave signal with a fast edge and a finely adjustable duty cycle is obtained through a special edge adjustment method, the high-frequency square wave signal cannot be output because the edge occupies two sampling points, and , so that the edge will be limited by the DDS sampling rate, and the edge time will be larger when the sampling rate is lower

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