It would be wonderful if enterprise high-speed PCB design methods could be as simple as connecting system schematic nodes and as beautiful as what you see on computer monitors. pcb stackup calculatorHowever, unless the designer is new to PCB design, or is extremely lucky, the actual PCB design process is usually not as easy as the circuit structure design they are engaged in. PCB designers face many new challenges before the ultimate goal of design research can affect normal management work and someone can affirm performance issues. This is precisely because of the current state of economic high-speed PCB design - design related rules and design technical guidelines continue to innovate and develop, if not lucky, they will form to provide a national successful solution to this solution.

The vast majority of PCBS are proficient in the basic principles and interactions of PCB devices that affect enterprises and society. 1 oz vs 2 oz The various information data that constitutes the input and output of the circuit board can be transmitted to the schematic designer of the quality standard with the possibility that we know ourselves a little or even become possible without a little do not know what will happen after the small schematic connection is converted into a printed circuit copper wire Professional layout designers through mutual exchanges and cooperation results. Usually, the schematic designer is responsible for the success or failure of the final board. However, the more schematic designers know about good layout technicians, the better the chances of avoiding some major safety issues for students.

If high-density FPgas are included in the design, there are many challenges that can be encountered before a well-designed schematic. Including hundreds of inputs and outputs, operating frequencies in excess of 500 millihertz (which can be higher in some designs), and ball spacing as small as half a millimeter, all lead to unwanted interactions between design units.

Concurrent switching noise

The first challenge may be what is known as concurrent switching noise (SSN) or concurrent switching Output (SSO). A large number of high-frequency data streams will cause problems such as ringing and crosstalk on the data line, and ground rebound and power supply noise will also occur on the power supply and ground plane, affecting the performance of the entire circuit board.

In order to solve the problem of ringing and crosstalk on high-speed data lines, utilizing differential signals is a good first step. Since one line on the difference pair is the absorption line and the other line provides the source current, the induction effect can be completely eliminated. When using differential pairs to transmit data, because the current remains local, it helps reduce the "bounce" noise caused by the induced current in the loop. For radio frequencies up to hundreds of megahertz or even gigahertz, signal theory suggests that the maximum signal power can be transmitted in impedance matching. When the transmission lines do not match, reflections occur, and only part of the transmitted signal goes from the source to the receiver, while the rest reflects back and forth between the sending and receiving ends. Implementing differential signals on printed circuit boards will play an important role in impedance matching (among other things).

Differential routing design

Differential routing design is based on impedance controlled PCB principle. Its model is a bit like coaxial cable. On impedance-controlled PCBS, the metal plane layer can be used as a shielding layer, the insulator is FR4 laminate, and the conductor is the signal wiring pair (see Figure 1). The average dielectric constant of FR4 is between 4.2 and 4.5. Because the manufacturing error is not known, it may lead to excessive etching of the copper wire and eventually lead to impedance error. The most accurate way to calculate PCB line impedance is to use a field analysis program (usually two-dimensional, sometimes three-dimensional), which requires solving the Maxwell equation of the entire PCB directly in batches with finite elements. The software can analyze EMI effects based on track spacing, line width, line width and insulation height.