Multiport PDN Optimization With the Newton–Hessian Minimization Method

Power distribution system design methodology and capacitor selection for modern CMOS technology

Abstract: Power systems for modern complementary metal-oxide-semiconductor (CMOS) technology are becoming harder to design. One design methodology is to identify a target impedance to be met across a broad frequency range and specify components to meet that impedance. The impedance versus frequency profiles of the power distribution system components including the voltage regulator module, bulk decoupling capacitors and high frequency ceramic capacitors are defined and reduced to simulation program with integrated circuit emphasis (SPICE) models. A sufficient number of capacitors are placed in parallel to meet the target impedance. Ceramic capacitor equivalent series resistance (ESR) and ESL are extremely important parameters in determining how many capacitors are required. SPICE models are then analyzed in the time domain to find the response to load transients.

Signal Integrity Design for High-Speed Digital Circuits: Progress and Directions

Abstract: This paper reviews recent progress and future directions of signal integrity design for high-speed digital circuits, focusing on four areas: signal propagation on transmission lines, discontinuity modeling and characterization, measurement techniques, and link-path design and analysis.

Improving signal integrity in differential signal systems

Abstract: Over-terminating the differential mode impedance of a differential transmission line, such as an INFINIBAND™ cable, at the receiving end, improves the differential signal integrity for typical variations in termination network impedance component (e.g., resistor) and transmission line characteristics. Eye opening of the differential signal can be made larger with reduced attenuation but increased jitter compared to under-terminating the differential mode impedance. Because the differential signal quality (larger eye opening) is improved, data can be transmitted over a longer transmission line with the same transmitter and receiver.

Quantifying SMT decoupling capacitor placement in dc power-bus design for multilayer PCBs

Abstract: Noise on a dc power-bus that results from device switching, as well as other potential mechanisms, is a primary source of many signal integrity (SI) and electromagnetic interference (EMI) problems. Surface mount technology (SMT) decoupling capacitors are commonly used to mitigate this power-bus noise. A critical design issue associated with this common practice in high-speed digital designs is placement of the capacitors with respect to the integrated circuits (ICs). Local decoupling, namely, placing SMT capacitors in proximity to ICs, is investigated in this study. Multilayer PCB designs that employ entire layers or area fills for power and ground in a parallel plate structure are considered. The results demonstrate that local decoupling can provide high-frequency benefits for certain PCB geometries through mutual inductive coupling between closely spaced vias. The associated magnetic flux linkage is between the power and ground layers. Numerical modeling using an integral equation formulation with circuit extraction is used to quantify the local decoupling phenomenon. Local decoupling can effectively reduce high-frequency power-bus noise, though placing capacitors adjacent to ICs may limit routing flexibility, and tradeoffs need to be made based on design requirements. Design curves are generated as a function of power-bus layer thickness and SMT capacitor/IC spacing using the modeling approach to quantify the power-bus noise reduction for decoupling capacitors located adjacent to devices. Measurement data is provided to corroborate the modeling approach.

An efficient approach for power delivery network design with closed-form expressions for parasitic interconnect inductances

Abstract: Investigation of a dc power delivery network, consisting of a multilayer PCB using area fills for power and return, involves the distributed behavior of the power/ground planes and the parasitics associated with the lumped components mounted on it Full-wave methods are often employed to study the power integrity problem While full-wave methods can be accurate, they are time and memory consuming The cavity model of a rectangular structure has previously been employed to efficiently analyze the simultaneous switching noise (SSN) in the power distribution network However, a large number of modes in the cavity model are needed to accurately simulate the impedance associated with the vias, leading to computational inefficiency A fast approach is detailed herein to accelerate calculation of the summation associated with the higher-order modes Closed-form expressions for the parasitics associated with the interconnects of the decoupling capacitors are also introduced Combining the fast calculation of the cavity models of regularly shaped planar circuits, a segmentation method, and closed-form expressions for the parasitics, an efficient approach is proposed herein to analyze an arbitrary shaped power distribution network While it may take many hours for a full-wave method to do a single simulation, the proposed method can generally perform the simulation with good accuracy in several minutes Another advantage of the proposed method is that a SPICE equivalent circuit of the power distribution network can be derived This allows both frequency and transient responses to be done with SPICE simulation