The Development Of Digital Synthesis Two-Channel Function Generator

The theory and realization method of digital synthesis two-channel function generator has been researched in the thesis. These instruments have extensive applications in research and teaching. The research task has important significance for promoting the level of digital function generators in our country.At present, it is adopted analogue oscillator method in two-channel function generator in our country. The two signals cannot synchronize when they are integral rate of frequency, and these instruments can only generate a few function waveforms. Although the two-phase signal generator has used digital technology, which often adopts address counter to generate waveforms, it needs complex circuits and multi filters for different frequency bands. It has lower frequency resolution, narrower frequency band, and lower phase-adjust resolution. In order to resolve such technical problems, this research task is put forward by request of the company who produces signal generators.Referring to mass technical literatures, the direct digital synthesis (DDS) is the main technique of generating wave, some general DDS chips are produced, but they have not the capability of two-channel phase adjustment. According to the features of this research, the direct digital synthesis control logical circuit has been designed with complex programmable logical devices, which has phase adjust capability. The calibration model has been built, DC offset and amplitude gain of each channel can be calibrated by using keyboard of the instrument, this method insures the reliability of the instrument, and is convenient for produce and maintenance. By the cooperation of the hardware and software, synchronization has been resolved when two channel signals are integral rate of frequency, andrealized high phase adjust resolution in wide frequency band.Based on the request of the market, two-channel digital synthesis generator with low frequency must be developed at first, the technical features of the instrument have been decided, and the all circuits have been designed. By debugging the circuits and testing the features, the research target has been fully achieved, this kind of instrument has been mass produced.The main technical features of the instrument include: Frequency range is from 10uHz to 50KHz, frequency resolution is 10uHz. Phase-adjust range is 0.00 - 359.99 , phase resolution is 0.01 . The number of wave is arbitrary, external amplitude modulation is permitted. More than ten kinds of standard waveforms can be generated, such as sine, square, pulse, sweep. The output resistance is 50 output attenuation range is 0-60dB. The waveform amplitude range is 0.00 -10.0V, the DC voltage range is -10.0-10.0V.