Design And Realization Of Digital Part Of Phase Noise Analyzer Based On Phase Identification Method

With the increasing demand for the quality of signal source in the field of modern electronic system and communication,the phase noise as an important index to measure the quality of signal source has been paid more attention.In order to realize the high index measurement of phase noise,this paper starts from the hardware architecture of the phase noise test system based on the phase discrimination method,completes the circuit design of the digital part of the whole system,realizes the functions of high-speed data acquisition and large capacity data storage,and establishes the phase noise processing algorithm on the FPGA chip to extract the phase noise information of the measured signal effectively.The main contents of this paper are as follows:1.Low noise and high precision data acquisition.The noise introduced in the acquisition process has a great impact on the phase noise measurement.In this paper,the high-precision analog-to-digital conversion chip is selected,and the arithmetic average filtering and cross-correlation noise reduction algorithm are designed with FPGA to realize the high-precision and low-noise acquisition function of the signal acquisition module.2.Data mass storage technology.Because the phase noise algorithm needs a large number of data points and the FPGA on-chip storage resources are limited,this paper constructs a "FPGA + DDR3 SDRAM" storage architecture to store a large number of data points and provide a data source for algorithm operation.3.Design and implementation of phase noise measurement algorithm.The algorithm is based on the phase noise measurement by phase discrimination method,combined with the improvement of FIR low-pass filtering,Fourier transform and other digital signal processing methods,and determines the design framework of "phase information extraction + downsampling + cross correlation + power spectrum estimation".The power spectral density is measured on the hardware platform based on FPGA.The multi-resolution power spectral estimation is realized by combining the multi band power spectral density curves,and the phase noise information is obtained.The indicators of the digital system designed in this paper are as follows: the SNR of the signal acquisition process is not less than 90 dB;a single operation can store220 M and 16 bit data points;the algorithm can extract phase noise and realize the analysis frequency offset of 1Hz?2MHz through software display;Bottom noise :(RF in 10MHz)?-165 d Bc/Hz@1k Hz,?-170 d Bc/Hz@10k Hz,(RF in 100MHz)?-155 d Bc/Hz@1k Hz,?-165 d Bc/Hz@10k Hz.After the design verification,the final function of each module of the system is realized,and all meet the requirements of the indicators,and the system can effectively measure the phase noise of the measured signal.