Efficient Sensitivity Calculations for Optimization of Power Delivery Network Impedance

Abstract

This paper presents efficient algorithms for sensitivity calculations of power delivery network (PDN) impedance. The sensitivity algorithm is based on the adjoint system method. Efficient calculation of sensitivity is critical for optimization of complex PDNs. The frequency-domain design of a PDN is a multiobjective optimization problem, which is formulated as a minimax problem in this paper. The design variables are typically the decoupling capacitors (decaps). The objective function is the input impedance of the PDN calculated at relevant frequencies. This paper also presents an efficient algorithm for large-change sensitivity calculations. Based on this method, what-if scenarios can be simulated efficiently, such as the addition, modification, or relocation of a few decaps or a small change in the geometry.

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“…This resonance peak may induce a serious problem for high-speed digital devices. To reduce the resonance peaks in the low-frequency ranges, combining a PDN with a decoupling capacitor can be considered [30][31][32][33]. However, an interaction between the decoupling capacitor and the PDN impedance can generate an additional resonance peak or just shift its frequency.…”

Virtual Ground Fence for GHz Power Filtering on Printed Circuit Boards

“…Also, ten times thinner laminate is required to reduce the transfer impedance magnitude by 20 dB, which may not be feasible if high isolation levels are required. 3) Power islands: This technique is based on using a moat around the isolated area which is connected to the power supply using a narrow bridge [7], [8]. At resonance frequencies of the power planes, there is substantial noise coupling through the conducting bridge.…”