+Click the image to get the sch-rnd sheet
+In this simulation we are going to look at how a multi-stage RC filter behaves +when stimulated with different frequency sine waves. + +
+The single-sheet schematics contains the filter, the voltage source and +spice command symbol. +
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+In the ac analysis the simulation a DC solution is calculated first +then a small signal sinusoidal stimulus is applied over a range of +frequencies. The result is typically a graph with frequency on the X axis +and gain or phase on the Y axis. The AC analysis is often used to get +a transfer function. + +
+In our example, V1 specifies an 1V AC signal with a DC component of 0V +on the in network. The syntax for this is (see in V1's spice/params): +
+dc 0 ac 1 ++
+The frequency of the ac component is not specified because that will be +varied over a range by the analysis command. + +
+It contains the following script: +
+ac dec 10 1 100k + +settype decibel out +plot vdb(out) xlimit 1 100k ylabel 'small signal gain' + +settype phase out +plot cph(out) xlimit 1 100k ylabel 'phase (in rad)' + +let outd = 180/PI*cph(out) +settype phase outd +plot outd xlimit 1 100k ylabel 'phase (in deg)' ++
+The first line instructs spice to do the "ac analysis" in decade variation +mode (dec 10), to get a decade logarithmic output with 10 points in each +decade. It then specifies the range of interest for frequencies: anything +between 1 Hz and 100 kHz. +
+Then come three plots. The first is the output voltage in decibels, on +a logarithmic Y scale. Then the phase shift of the circuit, in radian +and converted to degrees. + +
+Because of the plot commands the output is a set of drawing (if ngspice is ran +on X): three graphs with one curve each. +
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+TODO Index: trunk/doc/tutorial/simulation/raw/06_passive_ac1.png =================================================================== Cannot display: file marked as a binary type. svn:mime-type = application/octet-stream Index: trunk/doc/tutorial/simulation/raw/06_passive_ac1.png =================================================================== --- trunk/doc/tutorial/simulation/raw/06_passive_ac1.png (nonexistent) +++ trunk/doc/tutorial/simulation/raw/06_passive_ac1.png (revision 7843) Property changes on: trunk/doc/tutorial/simulation/raw/06_passive_ac1.png ___________________________________________________________________ Added: svn:mime-type ## -0,0 +1 ## +application/octet-stream \ No newline at end of property Index: trunk/doc/tutorial/simulation/raw/06_passive_ac2.png =================================================================== Cannot display: file marked as a binary type. svn:mime-type = application/octet-stream Index: trunk/doc/tutorial/simulation/raw/06_passive_ac2.png =================================================================== --- trunk/doc/tutorial/simulation/raw/06_passive_ac2.png (nonexistent) +++ trunk/doc/tutorial/simulation/raw/06_passive_ac2.png (revision 7843) Property changes on: trunk/doc/tutorial/simulation/raw/06_passive_ac2.png ___________________________________________________________________ Added: svn:mime-type ## -0,0 +1 ## +application/octet-stream \ No newline at end of property Index: trunk/doc/tutorial/simulation/raw/06_passive_ac3.png =================================================================== Cannot display: file marked as a binary type. svn:mime-type = application/octet-stream Index: trunk/doc/tutorial/simulation/raw/06_passive_ac3.png =================================================================== --- trunk/doc/tutorial/simulation/raw/06_passive_ac3.png (nonexistent) +++ trunk/doc/tutorial/simulation/raw/06_passive_ac3.png (revision 7843) Property changes on: trunk/doc/tutorial/simulation/raw/06_passive_ac3.png ___________________________________________________________________ Added: svn:mime-type ## -0,0 +1 ## +application/octet-stream \ No newline at end of property