Design Of 2.5GSPS Arbitrary Waveform Synthesis And Modulation Module

Arbitrary Function Generator(AFG)is a multifunctional signal source that is widely used in various test and verification fields.It has the advantages of outputting various waveforms,continuous waveform phase,shortcut frequency and high frequency resolution.With the booming development in the field of electronic information and integrated circuits,there is an increasing demand for AFG’s output waveform type,frequency resolution,system sampling rate,storage depth and other metrics.How to achieve higher metrics requirements with limited FPGA resources has become a current challenge.This thesis proposes a waveform synthesis scheme based on address dynamic reconfigurable memory and a diverse digital modulation scheme.The final output of arbitrary/functional waveform and modulated waveform with 2.5GSPS sampling rate is achieved.The main research of this thesis includes:1.Research on arbitrary waveform synthesis technique.In order to realize the output of arbitrary waveform signals with shortcut frequency,this thesis proposes a multiplexed memory DDFS waveform synthesis scheme based on dynamic reconfigurable address.The waveform sample point storage depth is changed to avoid signal distortion caused by sample point extraction when synthesizing arbitrary waveforms.2.Compatible logic design for high sampling and deep storage waveform synthesis.In order to simultaneously achieve the specification requirements of 2.5GSPS sampling rate and 512 k storage depth.This thesis uses a multiplexed memory DDFS structure based on address dynamic reconfigurability for waveform synthesis.The waveform synthesis logic is divided into high frequency waveform synthesis logic and long period waveform synthesis logic.By multiplexing the same memory resources and parallelizing them,high frequency waveforms can be synthesized to achieve a 2.5GSPS sampling rate metric.By serializing the memory resources,long-period waveforms can be synthesized to achieve a 512 k memory depth metric.3.Design of a diverse modulation module.Digital implementation of IQ modulation function as well as frequency modulation,phase modulation and amplitude modulation of arbitrary waveforms.Modulation source signal is switchable and implemented by external ADC,internal DDFS structure,and dual-channel independent feature.A CIC filter module is designed to perform sample rate conversion of external modulation data to save ADC cost.For the digital IQ modulation,this paper utilizes a multiplexed memory DDFS structure with address dynamic reconfigurability,which can synthesize two orthogonal digital carrier signals.Test results show that the arbitrary waveform synthesis module designed in this thesis is capable of synthesizing a wide range of function waveforms,as well as synthesizing arbitrary waveform synthesis.It outputs signals with a bandwidth of up to500 MHz and a frequency resolution of up to 1μHz.Modulation module designed in this thesis can realize diverse modulation and functions such as amplitude modulation from0% to 120% of depth.