Research On High-Speed PCB Signal And Power Integrity Based On EBG Structure

The current development of electronic products characterized by high-speed,high-density,low-voltage,high-current,and complex diversity,PCB design must consider problems such as signal distortion,power supply noise,power supply affecting signal integrity,or signal affecting power supply.Power integrity(PI)as an important part of signal integrity which aims to provide a stable and reliable power distribution network(PDN)for electronic products.However,synchronous switching noise(SSN)is the main source of power noise that affects PDN's stability,so it is very important to study how to eliminate or reduce SSN.The electromagnetic bandgap(EBG)structure has attracted much attention in suppressing power supply noise.But most of the EBG structures used to suppress SSN have limited suppression bandwidth and high lower cutoff frequency,and almost all EBG structures are etched on the intact copper surface,which not only takes up valuable PCB wiring space,but may further deteriorate the transmission line signal integrity.Therefore,this thesis hopes that under the premise of ensuring the signal integrity of PCB high-speed circuits as much as possible,to design a broadband EBG structure that can effectively suppress SSN in the power distribution network.By expounding the relevant basic theories of signal integrity in high-speed PCBs to analyze the impedance characteristics of the transmission lines on the PCB and simulate various factors that affect the magnitude of crosstalk.It analyzes the generation of synchronous switching noise and its propagation mechanism in PDN from the circuit,and compares the advantages and disadvantages of traditional noise suppression methods.According to Mushroom-EBG and UC-EBG the two classic structure's structural characteristics,equivalent circuit model and band gap characteristics,proposed LG-EBG structures of single branch and double branch to apply to the grid copper layer of soft board which combined with the current wide application prospects of the soft and hard board characteristics and most of the existing EBG structure has a greater impact on the SI after destroying the reference copper layer when suppress the synchronization switching noise.Verified by HFSS19.0 simulation,the new EBG structure can obtain excellent suppression bandwidths of 0.63-7.52GHZ and 0.43-10.97GHZ at-30dB,which are respectively 2.77GHZ and 6.42GHZ higher than the traditional L-bridge suppression bandwidth of 0.65-4.77GHZ.At the same time,studied the factors that may affect the band gap characteristics of this type of EBG structure,such as the size of the periodic unit,the supporting medium,the copper layer and the L branch.Finally,carried out the PCB physical board production of LG-EBG structures to test and verify their actual SSN suppression with the vector network analyzer(VNA);and established an equivalent circuit model of LG-EBG structures to estimate and analyze the upper and lower cutoff frequencies.Through time domain co-simulation analyzed the eye diagram of new structures,it shows that the proposed LG-EBG structures of single branch and double branch can not only effectively suppress SSN,but also ensure the original signal integrity to a greater extent.