Power Integrity And Crosstalk Analysis In High-speed Circuits

The Signal Integrity in High-Speed circuit is becoming increasingly prominent. In thehigh frequency, signal transmission line is a function of the time and the location. Digitalsystem circuit design methodology has transformed step by step from experiential designmode to that with high-speed system-level based on theory of signal integrity.In this paper, we study crosstalk and power integrity in the high-speed circuit, which aimsat providing important parameters for the system circuit design. The main works includes:1. High frequency decoupling capacitors selected method is analyzed. From a singlecapacitor equivalent model, the mathematical model of the anti-resonance point with threedecoupling capacitors are Introducted, when the two decoupling capacitors is parallelled,power distribution network impedance is higher than the target impedance, it need to increasethe third decoupling capacitor. By increasing the capacitance of the third method can reducethe anti-resonant points of any two impedance.It need to increase decoupling capacitors untilmeet the requirements.2. The crosstalk noise problems are solved in the high-speed circuit. Firstly, the influenceof the different termination design and space of vias about crosstalk are studied. ThroughADS simulation softwares, the results are gained, which show that: Below800MHz, it cansuppress crosstalk well when protective line is shorted, near and far crosstalk noise is lessthan-40dB. While the frequency higher than1GHz, it requires to setting up more groundingholes along the protective lines, near and far crosstalk noise is less than-42dB. Therelationship between the holes’ spacing and resonance is analyzed; the holes’ spacing on theline is20mm, the resonant point move to4.310GHz, which provide important reference datafor the actual circuit board design.