TABLE OF CONTENTS This chapter introduces tools that work with Capture and Layout in the design and manufacturing of PCBs. Some of the tools are included with the OrCAD design suite, while others are completely independent of OrCAD. The tools that are part of OrCAD are PSpice and SPECCTRA; the independent tools discussed here are GerbTool, Microsoft Excel, and CAD drawing tools.
PSpice was used in Chap. 7 to develop PSpice subcircuit models for creating new Capture parts with simulation capabilities. In this chapter PSpice is used to simulate transmission lines. When used in conjunction with the design equations from Chap. 6 (and the design example in Chap. 9) PSpice can be of help in designing PCB-based transmission lines and in understanding transmission lines in general.
The circuit shown in Fig. 11-1 is used here to simulate a high-speed digital circuit (it was also used to generate the plots used to explain ringing in Chap. 6). The circuit consists of a driver gate with an output impedance of 10 ?, a 50- ? transmission line, and a receiving gate with an input resistance of 1 k ? and input capacitance of 15 pF. The PSpice parts used in the circuit are the following:
V 2 is VPULSE (from the Source library), the driver.
R1 is R (from the Analog library), the source resistance (output impedance) of the driver.
T1 is T (from the Analog library), the...
