| With the advancement of semiconductor technology,electronic systems continue to develop towards high density,high speed,low voltage and high current.In the face of this development trend,power deliver network(PDN)has gradually become the design focus in high-speed digital systems,which directly affects the performance of signal integrity,power integrity,and electromagnetic compatibility in the system.The decoupling design is an important foundation to ensure the normal operation of PDN.This paper focuses on the decoupling design method of PDN in high-speed circuit system.The main research contents and results are as follows:Since the shortcomings and deficiencies in the currently proposed PDN decoupling design methods,a PDN decoupling design method based on resonant cavity theory is proposed.By this method,the self-inductance at the port and the diffusion inductance between the ports on the power/ground plane pair are obtained according to the resonant cavity theory and its inductance approximation algorithm.On the basis of the derivation of the formula and the impedance curve in the frequency domain,it can be seen that the self-inductance and diffusion inductance play an important role in the decoupling design.Thus,a quantitative analysis and explanation of how the inductance affects the decoupling performance of the capacitor is made.The effective region for placing decoupling capacitors is divided according to the order of magnitude relationship between self-inductance and diffusion inductance on the power/ground plane pair.The port position in the effective area proposed in this paper can reduce the limitation of the inductance on the plane on the decoupling performance of the capacitor at high frequencies.Thereby,the decoupling efficiency of the capacitor is effectively improved.Finally,the optimal location of decoupling capacitors in the effective area is determined by the impedance of the decoupling port.Comparing the decoupling design algorithm proposed in this paper with other decoupling design methods,it can be seen that this method has a great improvement in reducing the number of decoupling capacitors and decoupling efficiency.Based on the situation that most of the decoupling design methods proposed can only decouple single port so far,the decoupling design method proposed in this paper can decouple multiple ports at the same time.For ports that need to be decoupled on the same power/ground plane pair,which anti-resonant frequency is determined by the size parameters and dielectric constant of the plane pair.Therefore,the decoupling capacitors selected based on the anti-resonant frequency can decouple each port that needs to be decoupled.While the decoupling efficiency depends on the location of the decoupling capacitor on the plane pair.By the comparative analysis,this article finally chose to use the mean square error to process the muti-port decoupling results to determine the position of each decoupling capacitor on the power/ground plane pair.In this way,multiple ports that need to be decoupled can be decoupled as a whole.Thereby,the redundancy of the decoupling capacitors due to port differences is reduced,and the decoupling design efficiency is improved.Compared with other muti-port decoupling design methods,the method proposed in this paper still has great advantages in terms of the number of decoupling capacitors used and the flatness of the impedance curve.In the view of the resonant cavity theory cannot be applied to irregularly shaped planes,so it is difficult to apply the algorithm proposed in this paper to irregularly shaped PDN.In this article,the irregular shape plane is connected by the regular shape plane through the combination of numerical calculation and resonant cavity theory.In this way,the impedance at the port at any position on the plane of the irregular shape can be calculated.Then by the decoupling design algorithm proposed in this paper,it is applied to the decoupling design of irregular shape PDN.Finally,the decoupling design algorithm of this paper is presented through a human-computer interaction software tool according to the App Designer tool of MATLAB.By entering the relevant parameters required for the decoupling design,the types of capacitors used in the decoupling design and their locations on the power/ground plane pair can be obtained,which provides great convenience for the decoupling design. |
