Effective Characteristic Impedance


Reading time ( words)

In a typical interconnect, there lie multiple places where capacitance plays a factor in the signal integrity. This includes the driver and receiver output/input capacitance, as well as the packages, vias, and the transmission lines. Failing to optimize these parameters can often lead to unwanted reflections, excessive radiated and or conducted emissions, and sometimes failure of components and systems.

Reflections can occur anytime there is an impedance mismatch on the line. Sources of mismatches are plentiful and include trace width changes, vias, stubs, reference plane changes, and even the so-called fiber weave effect. In this case, a trace can encounter a different dielectric constant depending on whether it is routed over glass or the epoxy resin in the dielectric material. 

In this investigation, it is the capacitive contribution of the different components that are of interest, and how they affect the characteristic impedance the driver sees. 

To read the rest of this article, click here.

Share


Suggested Items

AltiumLive Summit—Munich, Germany, Part 2

11/13/2017 | Pete Starkey, I-Connect007
Pete Starkey continues with his review of the AltiumLive PCB Design Summit held recently in Munich, Germany. The second day commenced with a new product launch. “Working together is hard” it read on the screen. Statistics indicated that 33% of new products were late getting to market, of which 28% were late due to insufficient collaboration, and up to 50% of potential revenue could be lost through being late to market. Then the screen read “NEXUS makes it easy!”

Performance Evaluation of Thin-Film Embedded Resistors

07/24/2017 | Dora Yang, PCBCart
Thin-film microstrip circuits have been widely applied in microwave communications, electronic countermeasures (ECM), and aerospace applications, etc. When manufacturing thin-film ICs, it is very important to apply deposited thin-film resistor material to fabricate high-accuracy and highly stable thin-film embedded resistors. Thin-film ICs call for thin-film resistors that meet stringent requirements.

Resins: Five Essentials to Achieve the Right Cure

12/19/2016 | Alistair Little, Electrolube
Last month, I looked at some of the critical things you need to consider before selecting your resin. Of course, when it comes to the choice and application of resins, there’s a lot of information to take in, and over the following months I hope to distill this and provide some useful tips and design advice that will help you in your quest for reliable circuit protection.



Copyright © 2017 I-Connect007. All rights reserved.