Matteo Cocchini

Return via connections for extending signal link path bandwidth of via transitions

This paper discusses a fast and accurate way to assess the impact of signal vias where the return current must change reference planes, including the effect of a return current via placed various distances from the signal via. The equivalent circuit includes capacitance of the via anti-pad as well as cavity effects.

Mutual External Inductance in Stripline Structures

Abstract—The Method of Edge Currents (MEC) proposed in our previous paper [1] is applied herein for calculating the mutual external inductance associated with fringing magnetic fields that wrap ground planes of a stripline structure. This method employs a quasi-static approach, image theory, and direct magnetic field integration. The resultant mutual external inductance is frequency-independent. The approach has been applied to estimating mutual inductance for both symmetrical and asymmetrical stripline structures. Offset of the signal trace from the centered position both in horizontal and vertical directions is taken into account in asymmetrical structures. The results are compared with numerical simulations using the CST Microwave Studio Software.

Noise coupling between signal and power/ground nets due to signal vias transitioning through power/ground plane pair

Signal vias are often used to move a signal from one PCB layer to another. As a result, these vias can penetrate power/ground plane pair and cause noise coupling (crosstalk) between signal and power/ground nets. This paper studies the noise coupling mechanism using a segmentation approach combined with a via capacitance model and a plane-pair cavity model. Noise coupling from signal to power/ground, and vice versa, is demonstrated in the modeling results.

Noise coupling between power/ground nets due to differential vias transitions in a multilayer PCB

Due to the increase in board density, routing traces on different layers becomes a widely used strategy. Through-hole vias are often used to connect these traces. Those vias that penetrate power/ground plane pairs could cause noise coupling between signal and power/ground nets. At the same time, the need for clean signal transmitted to receivers results in a wide use of differential signals. This paper studies the noise coupling mechanism caused by a differential pair of vias penetrating power/ground plane pair using a physics-based via-plane model combined with transmission line models for traces. A 26-layer printed circuit board with a pair of differential vias have been modeled. The simulated results clearly demonstrate the impact of ground vias and via stubs on noise coupling.

Design methodology for PDN synthesis on multilayer PCBs

This papers goal is to help designers go through a step-by-step process to design the decoupling strategy for the charge supply. The distance to the decoupling capacitors, the number of decoupling capacitors, and the inductance associated with the connection of the decoupling capacitor to the power and ground-reference planes will all influence how much charge is delivered.