Global circuit common node(ground) is "0", though "GND" is special synonym. Nodes names may be arbitrary character strings. It can be turned off by going to Tools=>Control Panel=>SPICE and unchecking "Accept 3K4 as 3.4K". This works for any of the multipliers above. LTspice will accept numbers written in the form 6K34 to mean 6.34K. This is necessary for compatibility with standard SPICE practice. A common error is to draft a resistor with value of 1M, thinking of a one Megaohm resistor, however, 1M is interpreted as a one milliohm resistor. Hence, 10, 10V, 10Volts, and 10Hz all represent the same number, and M, MA, MSec, and MMhos all represent the same scale factor(.001). Unrecognized letters immediately following a number or engineering multiplier are ignored. Below is a table of understood multipliers: That is, 1000.0 or 1e3 can also be written as 1K. Numbers can be expressed not only in scientific notation e.g., 1e12 but also using engineering multipliers. The "+" is removed and the remainder of the line is considered part of the prior line. options reltol=1e-4Ī continuation of the previous line. O The first non-blank character of a line defines the type of circuit element.Ī simulation directive, For example. O Letter case, leading spaces, blanks, and tabs are ignored. The node "0" is the global circuit common ground.īelow is an overview of the lexicon of LTspice: The line starting with "C1" declares that there is a 100pF capacitor between nodes n2 and ground. Note that the semicolon, " ", can be used to start a comment in the middle of a line.
The line starting with "R1" declares that there is a 1K resistor connected between nodes n1 and n2.
Any line starting with a "*" is a comment and is ignored. tran 3μ do a 3μs long transient analysis R1 n1 n2 1K a 1KOhm resistor between nodes n1 and n2Ĭ1 n2 0 100p a 100pF capacitor between nodes n2 and ground * The circuit below represents an RC circuit driven Lines can be comments, circuit element declarations or simulation directives. The order of the lines between the comment and end is irrelevant. Any lines after the line ".END" are ignored. The last line of the netlist is usually simply the line ". The first line in the netlist is ignored, that is, it is assumed to be a comment. The circuit to be analyzed is described by a text file called a netlist. General Structure and Conventions General Structure and Conventions
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