A Method on Realizing Signal Generator for Arbitrary Waveform

Abstract

The basic approach of generating arbitrary waveform is the digital synthesis method. Appling this method, one first samples and quantifies a period of the signal waveform to be generized, memorizes the obtained binary waveform data in a memory, and then reads it via hardware circuit in certain sequence, converts the data via digital-to-analog (DA) circuit, finally output the analog waveform through a filter. In this work, an arbitrary waveform generator (AWG) is designed based on the theory of direct digital synthesis (DDS)[1-7]and on the analysis of the performance of the output signal. The design uses a field programmable-gate-array (FPGA)[3]chip to utilize the AWG. The preset and display of the output frequency and phase are controlled by a micro computer unit (MCU). The artribary waveform data can be downloaded and updated from a communication interface. The AWG can produce a high-resolution arbitrary waveform. The dissertation focuses on hardware circuit design, which has been accomplished, including power supply module, MCU system, high-speed DA converter, and filter, etc. The experimental prototype of the AWG has been made and tested systemly.At the end of the dissertation, the measurement result of the system is given and its error is analyzed. It is shown the AWG can output a sine wave, a triangle wave, a sawteeth wave, or a square wave within the frequency range from 0.01Hz to 15MHz with the step of 10mHz, or output an arbitrary waveform within the range from 0.01Hz to 20kHz.