The Design Of Analog Channel Of Arbitrary Waveform Generator With 4GSPS Sample Rate

The arbitrary waveform generator plays an important role in the military and civil test fields,analog channel is the last stage on the signal path of the arbitrary waveform generator,its performance is directly related to all the indicators of the arbitrary waveform generator.Therefore,research on analog channel contributes to improve the performance of arbitrary waveform generator.The research content of this paper belongs to the “4GSPS Arbitrary Waveform Generator” project,the project indicators are regard as the goal to achieve.This article's work is mainly as follows:1?The principle of waveform synthesis technology used in this project,which is DDWS technology,was introduced and analyzed.Combined with the output signal index requirements of analog channels,the circuit scheme that meets the requirements of this paper was designed.2?The hardware circuit is implemented one by one based on the proposed circuit scheme.Mainly includes: 600 MHz bandwidth elliptical LC filter design for DC-coupled channel that filtering requirements;Amplitude control circuit design for DC-coupled channel and direct DAC channel based on ? attenuator and op-amp;Offset control circuit based on op-amp and DAC,which realizes the-1.5V~+1.5V biasing range and 4-digit digital offset accuracy;AC coupling channel's amplitude control circuit design based on RF amplifier,op-amp and digital step attenuator.After completing the corresponding circuit design,using ADS2016,Pspice A/D and other related software to finish the circuit simulation and verification.3 ? A set of FPGA-based control plan is designed and realized for the control communication between the analog channel and the host computer,so that the host computer can control and adjust the output performance of the analog channel in real time.After the circuit design is completed,the principle of parameter correction was analyzed,and the amplitude and offset indexes of the analog channel output were corrected.A complete test platform was built,and the indicators of the analog channel were thoroughly tested,finally listed some typical results in the paper.Finally,this article realizes the analog channel circuit module of "4GSPS Arbitrary Waveform Generator",which has three output modes: DC coupling channel,AC coupling channel and direct DAC output channel.The DC coupling channel's sine wave output bandwidth reaches 600 MHz and has arbitrary waveform output capability.The AC coupling channel has the highest bandwidth among the three output modes,which's bandwidth ranging from 4MHz to 1.5GHz,and possesses an amplitude flatness index which is better than ±2dB.The direct DAC channel takes the bandwidth and output amplitude dynamic range both into consideration,and achieves an amplitude output of 1.2Vpp in the 1GHz bandwidth.