The Design And Implementation Of The Digital Channel Of Arbitrary Waveform Module

Arbitrary waveform generator is the special signal source which has all the characteristics of the signal source. In the current communication test systems, the single channel arbitrary waveform generator can not meet the requirements of precision and parameters of the test. In order to meet the development of technology and the accuracy requirement of the test system, the excitation signal which has dual channel even multi-channel is needed, and the arbitrary waveform generator which can support the multi- institutional and high precision should be designed.Under the research background of the portable vector signal source project, this paper emphasizes the baseband waveform technology under the arbitrary waveform mode and the changeable sample ratio processing technology of the multi- rate arbitrary waveform signal. Based on the thought of software radio and the hardware platform of DSP+FPGA+DDR3+DA in this paper, the storage rate of baseband signal is successfully realized with a rate as high as 800 MSa/s and the signal reconstruction can be an many as 200 interpolation by way of the program design, the test simulation and verification.The overall scheme of the project which includ es the multi-rate baseband signal processing and the DAC of digital arbitrary waveform is introduced in this paper. The multi-rate baseband signal processing contains the following three modules: Firstly, the design of the control and data path between FPGA and DSP which can link the bridge between FPGA and DSP. Second ly, the design of DDR3 SDRAM memory storage module, which can ensure the high-speed write or read operations of the digital baseband signal and realize the playback of the digital baseband signal by setting the parameter, simulating and verifying the DDR3 SDRAM memory controller. Third ly, the design of variable-rate processing module, which can effectively filter out mirrored component of arbitrary waveform and inhibit harmonic components, thus obtaining a smooth and integrated arbitrary waveform signal by a design of combining FIR + CIC. The DAC of digital arbitrary waveform is another important aspect of this paper. Convert the arbitrary waveform signal conducted by FPGA into analog signal by high-speed DAC. Taking the analog signal into the RF module, the output of the waveform can be realized by the corresponding signal conditioning circuit.A set design technique of digital path for arbitrary waveform generator module is provided in this paper. O ne part of the module is realized in Airtx- 7 series’ FPGA, and the other part is realized on the D/A board, verifying the various modules by using spectrum analyzer and software testing tools like ChipScope, realizing the generation of the double-channel arbitrary waveform, meeting the requirements of digital circuits.