docs/wiki/geda-grcsan.html

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  13 <h1 class="sectionedit1" id="geda_gaf_rf_cascade_symbols_and_netlister">gEDA/gaf RF Cascade Symbols and Netlister</h1>
  14 <div class="level1">
  15
  16 <p>
  17 by: Dan McMahill
  18 </p>
  19
  20 <p>
  21 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>
  22 </p>
  23
  24 <p>
  25 December 3rd, 2003
  26 </p>
  27
  28 </div>
  29 <!-- EDIT1 SECTION "gEDA/gaf RF Cascade Symbols and Netlister" [1-173] -->
  30 <h2 class="sectionedit2" id="overview">Overview</h2>
  31 <div class="level2">
  32
  33 <p>
  34 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/>
  35
  36 The basic steps involved with using gEDA as the frontend for Cascade simulations are:
  37 </p>
  38 <ol>
  39 <li class="level1"><div class="li"> Create schematics of the circuit.</div>
  40 </li>
  41 <li class="level1"><div class="li"> Extract the netlist.</div>
  42 </li>
  43 <li class="level1"><div class="li"> Run Cascade.</div>
  44 </li>
  45 </ol>
  46
  47 </div>
  48 <!-- EDIT2 SECTION "Overview" [174-630] -->
  49 <h2 class="sectionedit3" id="requirements">Requirements</h2>
  50 <div class="level2">
  51
  52 <p>
  53 You will need the following programs to be installed:
  54 </p>
  55 <ul>
  56 <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>
  57 </li>
  58 <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>
  59 </li>
  60 </ul>
  61
  62 </div>
  63 <!-- EDIT3 SECTION "Requirements" [631-1103] -->
  64 <h2 class="sectionedit4" id="creating_schematics">Creating Schematics</h2>
  65 <div class="level2">
  66
  67 <p>
  68 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/>
  69
  70 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.
  71 </p>
  72
  73 </div>
  74 <!-- EDIT4 SECTION "Creating Schematics" [1104-1748] -->
  75 <h2 class="sectionedit5" id="extracting_the_cascade_input_file">Extracting the Cascade Input File</h2>
  76 <div class="level2">
  77
  78 <p>
  79 To extract the Cascade input file, run:
  80 </p>
  81 <pre class="code">gnetlist -g cascade -o test.cas file1.sch [file2.sch ...]</pre>
  82
  83 <p>
  84 For the example file contained in this archive, you can run:
  85 </p>
  86 <pre class="code">gnetlist -g cascade -o example.cas example.sch</pre>
  87
  88 <p>
  89 The netlist will be left in <strong><code>example.cas</code></strong>.
  90 </p>
  91
  92 </div>
  93 <!-- EDIT5 SECTION "Extracting the Cascade Input File" [1749-2078] -->
  94 <h2 class="sectionedit6" id="running_cascade">Running Cascade</h2>
  95 <div class="level2">
  96
  97 <p>
  98 Cascade is exceptionally simple to run. Just run:
  99 </p>
 100 <pre class="code">cascade example.cas &gt; example.out</pre>
 101
 102 <p>
 103 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.
 104 </p>
 105
 106 </div>
 107 <!-- EDIT6 SECTION "Running Cascade" [2079-2393] -->
 108 <h2 class="sectionedit7" id="appendix_a_--_symbols_in_the_library">Appendix A -- Symbols in the Library</h2>
 109 <div class="level2">
 110
 111 <p>
 112 Please note that all instances must have the <strong><code>refdes=</code></strong> attribute set.
 113 </p>
 114
 115 </div>
 116 <!-- EDIT7 SECTION "Appendix A -- Symbols in the Library" [2394-2519] -->
 117 <h3 class="sectionedit8" id="sources_cascade-source">Sources (cascade-source)</h3>
 118 <div class="level3">
 119
 120 <p>
 121 Source.
 122 Attributes:
 123 </p>
 124 <ul>
 125 <li class="level1"><div class="li"> C=Carrier level in dBm. Optional.</div>
 126 </li>
 127 <li class="level1"><div class="li"> CN0=Carrier to Noise Spectral Density Ratio in dBm/Hz. Optional.</div>
 128 </li>
 129 <li class="level1"><div class="li"> CN=Carrier to Noise Ratio in dB. Optional.</div>
 130 </li>
 131 <li class="level1"><div class="li"> BW=Signal Bandwidth in Hz. Optional, but requred if CN= is used.</div>
 132 </li>
 133 </ul>
 134
 135 </div>
 136 <!-- EDIT8 SECTION "Sources (cascade-source)" [2520-2798] -->
 137 <h3 class="sectionedit9" id="defaults_cascade-default">Defaults (cascade-default)</h3>
 138 <div class="level3">
 139
 140 <p>
 141 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.
 142 Attributes:
 143 </p>
 144 <ul>
 145 <li class="level1"><div class="li"> RIN=Default block input resistance in Ohms. Optional.</div>
 146 </li>
 147 <li class="level1"><div class="li"> ROUT=Default block output resistance in Ohms. Optional.</div>
 148 </li>
 149 <li class="level1"><div class="li"> RHO=Default third order distortion correlation coeffcient. Optional.</div>
 150 </li>
 151 </ul>
 152
 153 </div>
 154 <!-- EDIT9 SECTION "Defaults (cascade-default)" [2799-3458] -->
 155 <h3 class="sectionedit10" id="elements">Elements</h3>
 156 <div class="level3">
 157
 158 <p>
 159 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
 160 only. The currently available element symbols are: Attributes:
 161 </p>
 162 <div class="table sectionedit11"><table class="inline">
 163         <tr class="row0">
 164                 <td class="col0">cascade-amp</td><td class="col1">Amplifier</td>
 165         </tr>
 166         <tr class="row1">
 167                 <td class="col0">cascade-filter</td><td class="col1">Filter</td>
 168         </tr>
 169         <tr class="row2">
 170                 <td class="col0">cascade-mixer</td><td class="col1">Mixer</td>
 171         </tr>
 172         <tr class="row3">
 173                 <td class="col0">cascade-transformer</td><td class="col1">Transformer</td>
 174         </tr>
 175         <tr class="row4">
 176                 <td class="col0" colspan="2"> </td>
 177         </tr>
 178         <tr class="row5">
 179                 <td class="col0" colspan="2"> Table 1: Element Types </td>
 180         </tr>
 181 </table></div>
 182 <!-- EDIT11 TABLE [3852-3988] --><ul>
 183 <li class="level1 node"><div class="li"> Gain is specified by one of the following:</div>
 184 <ul>
 185 <li class="level2"><div class="li"> <strong>G</strong>=Power gain in dB.</div>
 186 </li>
 187 <li class="level2"><div class="li"> <strong>GP</strong>=Power gain in dB.</div>
 188 </li>
 189 <li class="level2"><div class="li"> <strong>GV</strong>=Voltage gain in dB.</div>
 190 </li>
 191 </ul>
 192 </li>
 193 <li class="level1"><div class="li"> <strong>NF</strong>=Noise Figure in dB. Optional.</div>
 194 </li>
 195 <li class="level1"><div class="li"> <strong>IIP3</strong>=Input Third Order Intercept Point in dBm. Optional.</div>
 196 </li>
 197 <li class="level1"><div class="li"> <strong>RIN</strong>=Block input resistance in Ohms. Optional.</div>
 198 </li>
 199 <li class="level1"><div class="li"> <strong>ROUT</strong>=Block output resistance in Ohms. Optional.</div>
 200 </li>
 201 <li class="level1"><div class="li"> <strong>RHO</strong>=Third order distortion correlation coeffcient. Optional.</div>
 202 </li>
 203 </ul>
 204
 205 </div>
 206 <!-- EDIT10 SECTION "Elements" [3459-4416] -->
 207 <h2 class="sectionedit12" id="example">Example</h2>
 208 <div class="level2">
 209
 210 <p>
 211 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.
 212 </p>
 213
 214 </div>
 215 <!-- EDIT12 SECTION "Example" [4417-4605] -->
 216 <h3 class="sectionedit13" id="example_schematics">Example Schematics</h3>
 217 <div class="level3">
 218
 219 <p>
 220 Figure 1 shows the schematic of a simple receiver signal chain.<br/>
 221
 222 Figure 2 shows the contents of the example.cas file.
 223 </p>
 224 <div class="table sectionedit14"><table class="inline">
 225         <tr class="row0">
 226                 <td class="col0"> <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>
 227         </tr>
 228         <tr class="row1">
 229                 <td class="col0"> <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>
 230         </tr>
 231 </table></div>
 232 <!-- EDIT14 TABLE [4755-4828] -->
 233 </div>
 234 <!-- EDIT13 SECTION "Example Schematics" [4606-4829] -->
 235 <h3 class="sectionedit15" id="netlist_the_design">Netlist the Design</h3>
 236 <div class="level3">
 237
 238 <p>
 239 To netlist the design, run:
 240 </p>
 241 <pre class="code">gnetlist -g cascade example.cas example.sch</pre>
 242
 243 </div>
 244 <!-- EDIT15 SECTION "Netlist the Design" [4830-4944] -->
 245 <h3 class="sectionedit16" id="run_the_analysis">Run the Analysis</h3>
 246 <div class="level3">
 247
 248 <p>
 249 Run the analysis with:
 250 </p>
 251 <pre class="code">cascade example.cas</pre>
 252
 253 </div>
 254 <!-- EDIT16 SECTION "Run the Analysis" [4945-5028] -->
 255 <h2 class="sectionedit17" id="document_revision_history">Document Revision History</h2>
 256 <div class="level2">
 257 <div class="table sectionedit18"><table class="inline">
 258         <tr class="row0">
 259                 <td class="col0">December 3rd, 2003</td><td class="col1">Created cascade.tex</td>
 260         </tr>
 261 </table></div>
 262 <!-- EDIT18 TABLE [5068-5108] -->
 263 </div>
 264 <!-- EDIT17 SECTION "Document Revision History" [5029-] --></body>
 265 </html>