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What is SPICE?

Circuit Simulation Flow and Device Models

Current circuit simulation flows according the the following below: 'Circuit Description' → 'Circuit Analysis' → 'Circuit Results Output'
GUI (Graphical User Interface), software supplied in a single package that allows for intuitive operation using computer graphics.

Previously the [the xxx description] shown to the right of'Circuit Analysis' below was input using a text editor.
Now, the circuit diagram input using the circuit schematic editor is converted in netlist, delivered to the analysis engine, and the simulation automatically executed.

Here, please pay attention to the Model Parameter Descriptions below. Also, please note the Device Models in the previous section.

Device Model・・・
Analytical expression developed based on theoretical and experimental study

Device Model = Analytical Expression (variables and constants that make up this Analytical Expression are model parameters)
In other words, device parameters are used to reproduce the actual element characteristics on a simulator.

Circuit Description

Circuit Analysis

Analysis Results Output

Input using a Circuit Schematic Editor Input using a Circuit Schematic Editor
[Resistor Element Description] R1 n1 out1 1000    
[Capacitor Element Description] C1 out1 0 5p    
[MOS Transistor Description] M1 out1 n2 0 0 mn1
[Independent Voltage Source Description] Vpulse n2 0 pulse
(0 3 20n 2n 2n 100n 200n)
[Transient Analysis Description] .TRAN 0.2n 220n      
[Model Parameter Description] .model nm1 nmos (level=3 vto=0.65 tox=0.018u nsub=1e15 uo=500
+ ucrit=4.5e4 uexp=0.05 tpg=1 ld=0.02u xj=0.05u js=6m pb=0.94
+ cj=3.00e-4 cjsw=0.8n cgdo=0.24n cgso=0.20n cgbo=0.021n
rd=1 rs=1)
Waveform Display Waveform Display
SPICE Models

Electronics
Fundamentals