NEW! Download the feature-rich application version of the trace analyzer. NEW! Download the feature-rich application version of the trace analyzer.Layer Stackup File Format
Trace File Format
Reading Fiel from Local System
Writing Fiel to Local System
Transmission line impedance has long been an important subject for microwave and RF engineers. With the advancement in digital technologies, especially when the clock and/or data rate reached multiple gigahertz (GHz), designers of printed circuit board (PCB) and package have to care about the trace impedance in order to maintain the signal integrity (SI). The demand for impedance calculators rises dramatically.
I wrote several trace impedance calculators before and deployed on my EE Circle website. The core of those applets were all based on empirical formulas that are available in the transmission line handbook. I got user feedback from time to time complaining about the accuracy of those calculators. I realized that there were no easy fixes unless I study the problem thouroughly in the context of solving Maxwell's equations for 2D geometry. Three years ago, I started the quest of finding a better solution in my spare time. The result is this Trace Impedance Analyzer applet. My goal is to make it versatile and accurate. Hopefully, it will be adopted by my colleagues who need to know the characteristic impedance for single, coupled, or multi-trace transmission-line structures.
This applet employs many Java Swing elements that requires the browser support of J2SE (JDK) 1.2 or higher. If needed, please visit Sun's website to dowload the latest JRE installation with browser plug-in.
For a first-time user, it is highly recommended to get familiar with the GUI. It may even be more helpful to print a hard copy while using the above applet.
Getting numbers are easy, getting correct number are not. The following pages illustrate the accuracy of this tool in agreement with published data to within 3% of error. Each page has embeded a specialized version of Trace Analyzer applet. User can also use them as templates.
Another example, interesting but not benchmarked, contains four traces that are broad-side coupled CPW lines.
In both stackup and trace files, any line starting with the "#" sign is a comment statement.
User can specify the unit in the z-direction by a statement in form of
Unit unit_name
where unit_name can be one of the followings: {in, cm, mm, mil, um, nm}.
All materials used in a specific layer stackup have to be defined. A material definition is in form of
material material_name
type = type
er = er
tand = tanD
mr = mr
sigma = sigma
;
where
Then, the stackup file contains several interleaved dielectric and metal layer definition statements.
A dielectric layer is specified by
layer material_name
thickness = thickness
;
where material_name should be among the defined dielectric material names. thickness is a numerical value measured by the z unit.
A metal layer is specified by
layer material_name
index = metal_layer_index
thickness = thickness
under_cut = 0.0
trace_over_boundary = yes_or_no
# between dielctric Layers 1 and 2
z_offset = 0.0
;
where material_name should be among the defined conductor material names. metal_layer_index is an integer value (The top layer has index 1). thickness is a numerical value measured by the z unit. yes_or_no for the "trace_over_boundary" attribute can be "yes" if the trace bottom side coincide with the dielectric layer boundary, or "no" if the trace top side align with the dielectric layer boundary.
# Tech file content # generated by EE Circle TraceAnalyzer # on 9-29-2004 at 11:20 # Unit Unit mil # BEGIN material Copper material Copper type = conductor er = 1.0 tand = 0.0 mr = 1.0 sigma = 7.0E7 ; # END material Copper # BEGIN material Er_4.7 material Er_4.7 type = insulator er = 4.7 tand = 0.02 mr = 1.0 sigma = 0.0 ; # END material Er_4.7 # BEGIN material air material air type = insulator er = 1.0 tand = 0.0 mr = 1.0 sigma = 0.0 ; # END material air # BEGIN material Er_5.23 material Er_5.23 type = insulator er = 5.23 tand = 0.02 mr = 1.0 sigma = 0.0 ; # END material Er_5.23 # BEGIN material FR4 material FR4 type = insulator er = 4.2 tand = 0.02 mr = 1.0 sigma = 0.0 ; # END material FR4 # 1: The 1-th dielectric layer layer air thickness = 10.0 ; # 2: The 1-th metal layer layer Copper index = 1 thickness = 2.8 under_cut = 0.0 trace_over_boundary = yes # between dielctric Layers 1 and 2 z_offset = 0.0 ; # 3: The 2-th dielectric layer layer Er_5.23 thickness = 8.0 ; # 4: The 2-th metal layer layer Copper index = 2 thickness = 5.0 under_cut = 0.0 # constructed with entire_plane trace_over_boundary = yes trace_over_boundary = no # between dielctric Layers 2 and 3 z_offset = 0.0 ; # 5: The 3-th dielectric layer layer air thickness = 10.0 ;
User can specify the unit in the x-direction by a statement in form of
Unit unit_name
where unit_name can be one of the followings: {in, cm, mm, mil, um, nm}.
Next, the total number of traces is specified by a statement in form of
Num number_of_traces
Then, each trace is specified by
Trace metal_layer_index x_left width s_or_g;
where
# Trace file # generated by EE Circle Trace Analyzer # on 9-30-2004 at 11:23 # Unit Unit mil # Number of metal layers Num 2 # Traces arranged as: index x_coord width grounded Trace 1 10.0 10.0 s; Trace 1 25.0 10.0 s;
Regular applet is intrinsically prohibited to read and write files from/to local computer. Although there are work-around solutions for the applet to gain read/write access to the local file system, they usually pose threat to the security of the browsers and the client computer. A quasi-I/O scheme is designed here to transfer the text content of the files using an intermediate pot-up Java text window. The read and write procedures are described below:
User first opens the local text file in a text editor such as Notepad. Then, select and copy the entire file content. Follow the applet menu item for opening a file to get a pop-up window. Paste the copied text into the pop-up window, click "Done" button to complete the file reading process.
Follow the applet menu item for saving a file to get a pop-up window with all the exported text content. Move the mouse anywhere inside the pop-up window and click once, then user Ctrl-A to select the entire text, and Ctrl-C to copy. Now, open a local text editor, use Ctrl-V to paste the text, then save the file in local file system.
A Yahoo discussion group named TraceAnalyzer has been created to user comments and feedback about this tool.
Due to the time constraint, We are not be able to respond to all messages timely.