<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <head> <title></title> <link rel="stylesheet" media="screen" type="text/css" href="./style.css" /> <link rel="stylesheet" media="screen" type="text/css" href="./design.css" /> <link rel="stylesheet" media="print" type="text/css" href="./print.css" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> </head> <body> <div class="toc"> <div class="tocheader toctoggle" id="toc__header">Table of Contents</div> <div id="toc__inside"> <ul class="toc"> <li class="level1"><div class="li"><span class="li"><a href="#geda_gaf_rf_cascade_symbols_and_netlister" class="toc">gEDA/gaf RF Cascade Symbols and Netlister</a></span></div> <ul class="toc"> <li class="level2"><div class="li"><span class="li"><a href="#overview" class="toc">Overview</a></span></div></li> <li class="level2"><div class="li"><span class="li"><a href="#requirements" class="toc">Requirements</a></span></div></li> <li class="level2"><div class="li"><span class="li"><a href="#creating_schematics" class="toc">Creating Schematics</a></span></div></li> <li class="level2"><div class="li"><span class="li"><a href="#extracting_the_cascade_input_file" class="toc">Extracting the Cascade Input File</a></span></div></li> <li class="level2"><div class="li"><span class="li"><a href="#running_cascade" class="toc">Running Cascade</a></span></div></li> <li class="level2"><div class="li"><span class="li"><a href="#appendix_a_--_symbols_in_the_library" class="toc">Appendix A -- Symbols in the Library</a></span></div> <ul class="toc"> <li class="level3"><div class="li"><span class="li"><a href="#sources_cascade-source" class="toc">Sources (cascade-source)</a></span></div></li> <li class="level3"><div class="li"><span class="li"><a href="#defaults_cascade-default" class="toc">Defaults (cascade-default)</a></span></div></li> <li class="level3"><div class="li"><span class="li"><a href="#elements" class="toc">Elements</a></span></div></li> </ul> </li> <li class="level2"><div class="li"><span class="li"><a href="#example" class="toc">Example</a></span></div> <ul class="toc"> <li class="level3"><div class="li"><span class="li"><a href="#example_schematics" class="toc">Example Schematics</a></span></div></li> <li class="level3"><div class="li"><span class="li"><a href="#netlist_the_design" class="toc">Netlist the Design</a></span></div></li> <li class="level3"><div class="li"><span class="li"><a href="#run_the_analysis" class="toc">Run the Analysis</a></span></div></li> </ul> </li> <li class="level2"><div class="li"><span class="li"><a href="#document_revision_history" class="toc">Document Revision History</a></span></div></li></ul> </li></ul> </div> </div> <h1><a name="geda_gaf_rf_cascade_symbols_and_netlister" id="geda_gaf_rf_cascade_symbols_and_netlister">gEDA/gaf RF Cascade Symbols and Netlister</a></h1> <div class="level1"> <p> by: Dan McMahill </p> <p> This document is released under <a href="http://www.gnu.org/copyleft/fdl.html" class="urlextern" title="http://www.gnu.org/copyleft/fdl.html" rel="nofollow">GFDL</a> </p> <p> December 3rd, 2003 </p> </div> <!-- SECTION "gEDA/gaf RF Cascade Symbols and Netlister" [1-173] --> <h2><a name="overview" id="overview">Overview</a></h2> <div class="level2"> <p> This document describes the symbol library and gnetlist backend which support driving RF Cascade (<a href="http://rfcascade.sourceforge.net" class="urlextern" title="http://rfcascade.sourceforge.net" rel="nofollow">http://rfcascade.sourceforge.net</a>) simulations from the gEDA/gaf system. Cascade is a noise figure and distortion analysis tool geared towards radio receiver design.<br/> The basic steps involved with using gEDA as the frontend for Cascade simulations are: </p> <ol> <li class="level1"><div class="li"> Create schematics of the circuit.</div> </li> <li class="level1"><div class="li"> Extract the netlist.</div> </li> <li class="level1"><div class="li"> Run Cascade.</div> </li> </ol> </div> <!-- SECTION "Overview" [174-630] --> <h2><a name="requirements" id="requirements">Requirements</a></h2> <div class="level2"> <p> You will need the following programs to be installed: </p> <ul> <li class="level1"><div class="li"> A recent version of gEDA/gaf. To see if your version is recent enough, see if the directory <strong><code>$prefix/share/gEDA/sym/cascade</code></strong> exists. <strong><code>$prefix</code></strong> is the installation prefix for gEDA on your system.</div> </li> <li class="level1"><div class="li"> RF Cascade. The executable is usually called cascade. If you do not have Cascade available on your system, you will need to get a copy from <a href="http://rfcascade.sourceforge.net" class="urlextern" title="http://rfcascade.sourceforge.net" rel="nofollow">http://rfcascade.sourceforge.net</a>.</div> </li> </ul> </div> <!-- SECTION "Requirements" [631-1103] --> <h2><a name="creating_schematics" id="creating_schematics">Creating Schematics</a></h2> <div class="level2"> <p> When creating a block diagram in the gschem schematic editor, use only the symbols from the cascade library. Every block diagram must have a \cascadesource” element. In addition, the block diagram must be a simple cascade. No parallel paths or branches are allowed.<br/> All instances must have a unique reference designator. For a receiver block diagram, this is often times best achieved by manually entering them. The only restriction on reference designator names is that they contain no spaces. A descriptive name such as \RF Filter” or \First Mixer” is useful as it will show up in the cascade output report. </p> </div> <!-- SECTION "Creating Schematics" [1104-1748] --> <h2><a name="extracting_the_cascade_input_file" id="extracting_the_cascade_input_file">Extracting the Cascade Input File</a></h2> <div class="level2"> <p> To extract the Cascade input file, run: </p> <pre class="code">gnetlist -g cascade -o test.cas file1.sch [file2.sch ...]</pre> <p> For the example file contained in this archive, you can run: </p> <pre class="code">gnetlist -g cascade -o example.cas example.sch</pre> <p> The netlist will be left in <strong><code>example.cas</code></strong>. </p> </div> <!-- SECTION "Extracting the Cascade Input File" [1749-2078] --> <h2><a name="running_cascade" id="running_cascade">Running Cascade</a></h2> <div class="level2"> <p> Cascade is exceptionally simple to run. Just run: </p> <pre class="code">cascade example.cas > example.out</pre> <p> to run the analysis on the system contained in the file <strong><code>example.cas</code></strong> and write the results to the file <strong><code>example.out</code></strong>. Refer to the Cascade documentation for complete details. </p> </div> <!-- SECTION "Running Cascade" [2079-2393] --> <h2><a name="appendix_a_--_symbols_in_the_library" id="appendix_a_--_symbols_in_the_library">Appendix A -- Symbols in the Library</a></h2> <div class="level2"> <p> Please note that all instances must have the <strong><code>refdes=</code></strong> attribute set. </p> </div> <!-- SECTION "Appendix A -- Symbols in the Library" [2394-2519] --> <h3><a name="sources_cascade-source" id="sources_cascade-source">Sources (cascade-source)</a></h3> <div class="level3"> <p> Source. Attributes: </p> <ul> <li class="level1"><div class="li"> C=Carrier level in dBm. Optional.</div> </li> <li class="level1"><div class="li"> CN0=Carrier to Noise Spectral Density Ratio in dBm/Hz. Optional.</div> </li> <li class="level1"><div class="li"> CN=Carrier to Noise Ratio in dB. Optional.</div> </li> <li class="level1"><div class="li"> BW=Signal Bandwidth in Hz. Optional, but requred if CN= is used.</div> </li> </ul> </div> <!-- SECTION "Sources (cascade-source)" [2520-2798] --> <h3><a name="defaults_cascade-default" id="defaults_cascade-default">Defaults (cascade-default)</a></h3> <div class="level3"> <p> This symbol sets the default impedance levels as well as the correlation coeffcient used for third order distortion calculations. There are two versions of this symbol. One is used to set the defaults at the beginnng of the definition. The other can be placed in series with the cascade to change the defaults part way through. This is useful if you wish to change impedance levels in the middle of the receiver chain. Attributes: </p> <ul> <li class="level1"><div class="li"> RIN=Default block input resistance in Ohms. Optional.</div> </li> <li class="level1"><div class="li"> ROUT=Default block output resistance in Ohms. Optional.</div> </li> <li class="level1"><div class="li"> RHO=Default third order distortion correlation coeffcient. Optional.</div> </li> </ul> </div> <!-- SECTION "Defaults (cascade-default)" [2799-3458] --> <h3><a name="elements" id="elements">Elements</a></h3> <div class="level3"> <p> Cascade characterizes each block in a system by its gain and optionally noise figure and third order intercept point. As such, there is no distinction between various elements such as amplifiers, filters, and mixers. The gEDA/gaf RF Cascade symbol library contains different symbols for clarity in the diagram only. The currently available element symbols are: Attributes: </p> <table class="inline"> <tr> <td>cascade-amp</td><td>Amplifier</td> </tr> <tr> <td>cascade-filter</td><td>Filter</td> </tr> <tr> <td>cascade-mixer</td><td>Mixer</td> </tr> <tr> <td>cascade-transformer</td><td>Transformer</td> </tr> <tr> <td colspan="2"> </td> </tr> <tr> <td colspan="2"> Table 1: Element Types </td> </tr> </table> <ul> <li class="level1"><div class="li"> Gain is specified by one of the following:</div> <ul> <li class="level2"><div class="li"> <strong>G</strong>=Power gain in dB.</div> </li> <li class="level2"><div class="li"> <strong>GP</strong>=Power gain in dB.</div> </li> <li class="level2"><div class="li"> <strong>GV</strong>=Voltage gain in dB.</div> </li> </ul> </li> <li class="level1"><div class="li"> <strong>NF</strong>=Noise Figure in dB. Optional.</div> </li> <li class="level1"><div class="li"> <strong>IIP3</strong>=Input Third Order Intercept Point in dBm. Optional.</div> </li> <li class="level1"><div class="li"> <strong>RIN</strong>=Block input resistance in Ohms. Optional.</div> </li> <li class="level1"><div class="li"> <strong>ROUT</strong>=Block output resistance in Ohms. Optional.</div> </li> <li class="level1"><div class="li"> <strong>RHO</strong>=Third order distortion correlation coeffcient. Optional.</div> </li> </ul> </div> <!-- SECTION "Elements" [3459-4416] --> <h2><a name="example" id="example">Example</a></h2> <div class="level2"> <p> This appendix provides a simple example of the entire process of generating a schematic, producing a Cascade input file, running an analysis and looking at the result. </p> </div> <!-- SECTION "Example" [4417-4605] --> <h3><a name="example_schematics" id="example_schematics">Example Schematics</a></h3> <div class="level3"> <p> Figure 1 shows the schematic of a simple receiver signal chain.<br/> Figure 2 shows the contents of the example.cas file. </p> <table class="inline"> <tr> <td> <a href="media/geda/rf_cascade_figure1.jpg" class="media" target="_blank" title="geda:rf_cascade_figure1.jpg"><img src="media/geda/rf_cascade_figure1.jpg" class="media" alt="" /></a> </td> </tr> <tr> <td> <a href="media/geda/rf_cascade_figure2.jpg" class="media" target="_blank" title="geda:rf_cascade_figure2.jpg"><img src="media/geda/rf_cascade_figure2.jpg" class="media" alt="" /></a> </td> </tr> </table> </div> <!-- SECTION "Example Schematics" [4606-4829] --> <h3><a name="netlist_the_design" id="netlist_the_design">Netlist the Design</a></h3> <div class="level3"> <p> To netlist the design, run: </p> <pre class="code">gnetlist -g cascade example.cas example.sch</pre> </div> <!-- SECTION "Netlist the Design" [4830-4944] --> <h3><a name="run_the_analysis" id="run_the_analysis">Run the Analysis</a></h3> <div class="level3"> <p> Run the analysis with: </p> <pre class="code">cascade example.cas</pre> </div> <!-- SECTION "Run the Analysis" [4945-5028] --> <h2><a name="document_revision_history" id="document_revision_history">Document Revision History</a></h2> <div class="level2"> <table class="inline"> <tr> <td>December 3rd, 2003</td><td>Created cascade.tex</td> </tr> </table> </div> <!-- SECTION "Document Revision History" [5029-] --></body> </html>
