Hardware Design Of PXIe Dual-channel Arbitrary Waveform Generator

PXIe arbitrary waveform generator can not only produce standard waveforms with precisely adjustable waveform parameters and user-defined arbitrary waveforms,but also has the flexible scalability of modular instruments and multi-module synchronization characteristics.It is widely used in various testing and research fields,one of the development trends of modern test instruments.Due to the complexity of modern testing,there are higher requirements for the sampling rate,storage depth,waveform parameter adjustment ability and synchronization characteristics of arbitrary waveform generators.Focusing on the above problems,this Thesis deeply analyzes the waveform synthesis theory and signal conditioning methods,and completes the hardware design of PXIe dual channel arbitrary waveform generator with sampling rate of 800MSa/s and bandwidth of 80 MHz.The main work is as follows:1.Complete the hardware design of dual-channel waveform synthesis module.According to the realization characteristics of different waveform synthesis methods and the design requirements of different waveforms,the standard wave,arbitrary wave and pulse wave are synthesized separately.The phase separation parallel storage structure based on DDFS is used to realize standard waveform synthesis,and the sampling rate of the system is increased to 800MSa/s;The DDWS structure is used to synthesize arbitrary waveform,and the DDR3 SDRAM are used as waveform memory,which not only expands the storage depth to 512 MB each channel,but also saves the board area.High resolution pulse signal synthesis is realized by adjusting the rising / falling edge slope of pulse signal in real time.Using FPGA+DDR3 SDRAM+DAC architecture is to complete the hardware circuit design of waveform synthesis module.2.Complete the design of clock and multi-channel synchronization circuit.The data synchronization of data sending module and DAC conversion synchronization are the key to realize multi-channel synchronization;The multi DAC synchronization method based on JESD204 B interface and the method of synchronizing the sampling clock and trigger signal between multiple modules are analyzed.Complete the clock circuit design on the basis of taking into account the system clock requirements and synchronization requirements.The800 MHz fixed sampling clock required for synthesizing standard waveforms using phaselocked loop,and the 5.6?Hz?400MHz low noise variable sampling clock required for synthesizing arbitrary waveforms using the internal NCO of the DAC.3.Complete the hardware circuit design of 80 MHz bandwidth and dual-channel signal conditioning module.The spectrum characteristics of DAC output signal are analyzed,and a two-stage filter is designed to filter out the image frequency components generated by DDS system;Digital fine adjustment and analog coarse adjustment are used to realize amplitude adjustment with step of 0.16 d B and range of 15.5m Vpp ? 24Vpp;Use the original operational amplifier in the channel to build an addition and subtraction circuit to realize ±0.5Vpp DC offset control.A self calibration circuit is designed to solve the problem of inaccurate output of AWG output amplitude and DC bias due to time drift and zero drift.The system test results show that the PXIe dual-channel arbitrary waveform generator designed in this Thesis has a maximum sampling rate of 800 MSa / s and a storage depth of512 MB / channel;It can realize the synthesis of various standard waveforms and arbitrary waveforms.It can realize the signal output of DC?80MHz with 15.5m Vpp?24Vpp amplitude range,and the offset adjustment range of ±0.5Vpp.The synchronization deviation between channels is less than 100 ps,and the synchronization deviation between modules is less than 300 ps.