SPICE syntax and tutorial

The first line of any SPICE netlist is the title line. It is used for documentation purposes only. The next few lines usually tell SPICE which analysis will be performed and what the bounds of that analysis will be. For example, we may be requesting a time domain analysis of a circuit (called a transient analysis). The information as to how long the waveform is and what increments and what section of it are of interest is defined in this section of the code. SPICE netlists generally have one function, command, or element per line (Fig. 2.1). Also defined upfront are global constants, subcircuits (models) used repeatedly in the main circuit, and instructions on which nodes are of interest in the final solution, though this structure is not mandatory. 

The middle section of the code defines the circuit itself. The structure of each component is roughly similar. The first variable is the reference designator. The next variable is the number of nodes that the component 

In this line, resistor R1 is defined as a resistor connected from node 1 to node 2 with a value of 100 2. Several rules apply in defining components. Node 0 is reserved for ground. All circuits must have at least one ground connection. Also, reference designators are limited to alphanumeric characters (Fig. 2.2). Longer statements may be continued on the following line by using a + symbol as the first character to indicate a continuation from the previous line. 

The final line of any SPICE program must be the. END statement. Several basic analyses are used in this book. An explanation of each is given in the following paragraphs. 

For nonconvergence, the value of ITL1 should be increased to greater than 500, which increases the maximum allowed number of iterations to determine the solution. 

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