Free Trial

Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.

  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Share this Page URL
Help

Chapter 5. Transmission Lines > Comparison of On-Chip, Package, and PCB Traces

5.6. Comparison of On-Chip, Package, and PCB Traces

This section compares different transmission line types by their off-chip and on-chip levels: microstrip lines in a typical PCB motherboard, microstrip lines in a BT substrate package, and an on-chip wire. Figure 5.29 provides the geometry information for the motherboard and package traces. The lengths of the motherboard traces are 8cm and 16cm, whereas the package traces lengths are 6.56mm and 13.34mm. The on-chip wire uses the structure in the previous section, as shown in Figure 5.23. Figure 5.30 shows the converted RLGC parameters. As expected, the resistance of an on-chip wire is significantly higher than the package and PCB traces, and it is constant over a wide frequency range. This indicates that the skin effect, or proximity effect, is not so severe, whereas the resistance of the package and PCB traces shows that the skin effect is frequency-dependent. As shown in Figure 5.30, the resistance of the package trace is also higher than that of the PCB trace. This is because the cross section of the package trace is smaller, resulting in a smaller area for current. In the on-chip wire case, both the inductance and capacitance vary, even at extremely higher frequencies, indicating that the transmission line model is not a good choice for modeling on-chip wires.

Figure 5.29. Microstrip Geometries: PCB Motherboard and Package Traces



  

You are currently reading a PREVIEW of this book.

                                                                                                                    

Get instant access to over $1 million worth of books and videos.

  

Start a Free Trial


  
  • Safari Books Online
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint