Arbitrary Waveform Generator, The Amplitude-frequency Correction Method And The Modular Design

As a commonly used tool for signal generation,Arbitrary Waveform Generator has been widely used in modern electronic measurement, communications, aerospace, instrumentation and other industries. It can produce traditional waveforms, such as sine wave signals,triangle wave signals; and has achieved functions of frequency scan,frequency modulation,phase shift keying,frequency shift keying,amplitude modulation and other modulation,moreover it is able to generate artificial rendering arbitrary waveform.However, because of the zero-order hold character of DAC and the disparity of the devices in analog channels, DDS technology-based arbitrary waveform generator could lead to a distortion of the output signal amplitude and frequency. In certain situations, it will fail to meet the project requirements. So distorted amplitude and frequency correction is necessary.Based on the special hardware structure of Arbitrary Waveform Generator, this paper present a solution relying on digital filtering approaches to above problem called digital correction which has two different sampling methods as simple and multiple ways.This paper's main subject are as follows.1. DDS technology-based arbitrary waveform generator of amplitude-frequency distortion is analyzed, especially the theory of amplitude and frequency distortion caused by DAC's zero-order hold character.2. Different correction method, home and abroad, has been compared. The appropriate correction program of digital correction has been brought.3. The detail of realizing the FIR digital filter was discussed, so were the key issues of the specific design using FPGA.4. Two FIR digital filters were designed matching the 100MSPS and500MSPS Arbitrary Waveform GeneratorFPGA plays an important role in the DDS technology-based arbitrary waveform generator. And the FIR digital filter based on Distributed Algorithm can easily be realized within the FPGA. Two FIR digital filters were designed and manufactured in this paper. The measurement results showed that this correction method can effectively solve the distortion of amplitude and frequency.