Small signal AC analysis
Next we will analyze the frequency response of the circuit through Small signal AC analysis.
1. Set the waveform contents for Small signal AC analysis (Analysis/ Small Signal AC Analysis/ Waveform Viewer) as mentioned in the above topics. Here you have the option to set complex values where the waveform viewer would plot real, imaginary parts, phase and magnitude of EDSpice output, according to the selection made. Check the option Real and ACCEPT the setting.
2. The small signal AC analysis may be performed after setting up of parameters for the analysis from Analysis menu. Select Analysis | Small signal AC Analysis from the tree view on the left side of the window.
Set the values to:
Total point 10
Start frequency 10
End frequency 1MHz.
3. Set the Variation to Octave and select the option Diagram from the drop down ‘Results’ to obtain the result in graphical format.
General Form is
.AC OCT NO FSTART FSTOP
OCT stands for octave variation, and NO is the number of points per octave. FSTART is the starting frequency, and FSTOP is the final frequency. If this line is included in the input file, SPICE performs an AC analysis of the circuit over the specified frequency range.
4. After entering the values the information passed to the simulation engine is
.AC OCT 10 10 1MEG
5. After the commands have been received, the simulation engine parses the netlist generated, executes the selected analysis and stores the results in the output files RAWSPICE.RAW and EDSPICE.OUT.
6. Click on the RUN button to start the analysis. The simulator engine, on completion of analysis, gives a confirmation and the results of simulation are processed for presentation. The whole process is completed when the results are displayed in either graphical or textual form. The waveform viewer pops up with the result as shown below.
7. This curve shows the output with respect to the frequency.