Index: simulation/sim/06_passive_ac/06_passive_ac.svg =================================================================== --- simulation/sim/06_passive_ac/06_passive_ac.svg (nonexistent) +++ simulation/sim/06_passive_ac/06_passive_ac.svg (revision 8804) @@ -0,0 +1,690 @@ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Index: simulation/sim/06_passive_ac/index.html =================================================================== --- simulation/sim/06_passive_ac/index.html (nonexistent) +++ simulation/sim/06_passive_ac/index.html (revision 8804) @@ -0,0 +1,67 @@ + + +

06_passive_ac: freqency domain simulation: ac

+ +

Scope

+

+In this simulation we are going to look at how a multi-stage RC filter behaves +when stimulated with sine waves of various frequencies. + +

The schematics

+

+The single-sheet schematic contains the filter, directy usable in the PCB +workflow. +

+

+ +
Click the image to get the sch-rnd sheet; also requires this project.lht in the same directory
+

+ +

SPICE: what an ac simulation is

+

+In the ac analysis simulation a DC solution is calculated first +and 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. + +

Preparing for simulation

+ +The process is largely the same as in the +base example of dc op point. The simulation +setup in this example is called "freq domain characteristics". Below are +the summary of differences compared to +the trans analysis of a very similar circuit + + +

Modifications

+

+Our input source is not a stable DC voltage source anymore, but an AC source. +It's still a 'V' for voltage source, connected to CN1-2, but the AC field +is set to 1 (volt). Because of the AC field set, a spice AC analysis will +automatically use this voltage source to feed in various frequencies. + +

Sim setup: output config

+

+This simulation has two output configs, one for displaying the transfer +(in decibel) and one for the phase (in radian). The reason for specify them +in two separate output is the largely different y scale and unit. +

+The first output uses ac (dec) for analysis. This will feed in 10 +different frequencies per decade and caputre the output. This also means +the X axis, frequency, is logarithmic (common for frequency domain analysis). +

+The property to plot is vdb(out), which is the "voltage decibel" of +the network called out. Instead of the net name a component-port could be +specified within vdb(). +

+The second output uses anlaysis previous, which means no new simulation +is ran, but the data of the previous simulation is used. The presentation is +also a plot of "out", but using the cph() function, which is the phase in +radian. +

+

+ +
Simulation setup dialog, third tab, after execution
+

+ Index: simulation/sim/06_passive_ac/sim_run.png =================================================================== Cannot display: file marked as a binary type. svn:mime-type = application/octet-stream Index: simulation/sim/06_passive_ac/sim_run.png =================================================================== --- simulation/sim/06_passive_ac/sim_run.png (nonexistent) +++ simulation/sim/06_passive_ac/sim_run.png (revision 8804) Property changes on: simulation/sim/06_passive_ac/sim_run.png ___________________________________________________________________ Added: svn:mime-type ## -0,0 +1 ## +application/octet-stream \ No newline at end of property