.DC

In this topic:

Syntax

.DC inner_sweep_spec [RUNNAME=runname] [ SWEEP outer_sweep_spec ]
Spice compatible: 
.DC device_name start stop step
The remainder are SIMetrix 2.5 - 3.1 compatible: 
.DC TEMP start stop step
.DC PARAM param_name start stop step
.DC MODEL model [PARAM] mod_param_name start stop step

Instructs simulator to perform a DC sweep analysis. A dc analysis performs a dc operating point analysis for a range of values according to the sweep specification. SIMetrix DC analysis is not limited to sweeping a voltage or current source as with generic SPICE. Any mode defined by the general sweep specification (see General Sweep Specification) may be used although frequency sweep has no useful purpose.

inner_sweep_spec See General Sweep Specification for syntax. Defines sweep mode. DEVICE keyword is optional.
outer_sweep_spec If specified, analysis will be repeated according to this specification. See Multi Step Analyses for details.
device_name Component reference of voltage source, current source, resistor or controlled source to be swept. (Only voltage and current sources are SPICE compatible).
start Start value for sweep
stop Stop value for sweep
step Increment at each point
param_name Parameter name. This would be used in an expression to define a component or model value.
model_name Model name e.g. Q2N2222
model_parameter_name Model parameter name e.g. IS
runname If specified, the value for runname will be passed to the simulation data group as a string variable with name UserRunName. This may be used to identify which analysis generated the data which is useful when running netlists with multiple analyses defined.

If start is arithmetically greater than stop then step must be negative.

It is not necessary to declare parameters with .PARAM if using parameter sweep.

Examples

SPICE compatible. Sweep V1 from 0 to 5 volts in steps of 0.1 volt 
.DC V1 0 5 0.1
SIMetrix 3.1 compatible temperature sweep 
.DC TEMP 0 100 2
Decade (i.e. logarithmic) sweep. Sweep V1 from 1mV to 1V with 25 points per decade 
.DC V1 DEC 25 1m 1v

Note that the DEVICE keyword has been omitted. This is the default sweep mode for .DC.

Do 1000 Monte Carlo steps. This performs the same task as a Monte Carlo analysis applied to a DC operating point. In other products and earlier versions of SIMetrix this task would take a long time as the operating point is solved from scratch each time. With the mode described by the following example, the operating point need only be calculated from scratch once. All subsequent steps are seeded by the previous one and usually require only a few iterations. The end result is a sometimes spectacular increase in speed. 

.DC MONTE 1000

Examples of Nested Sweeps

Decade sweep at temperatures 0 to 100 in steps of 10 
.DC V1 DEC 25 1m 1v SWEEP TEMP STP 0 100 10
Note the STP keyword is necessary to signify the start-stop-step method of defining a linear sweep. Alternatively LIN can be used which defines the sweep in terms of the total number of points. The following is equivalent to the above: 
.DC V1 DEC 25 1m 1v SWEEP TEMP LIN 11 0 100
Do 100 run Monte Carlo analysis for temperature sweep 
.DC TEMP 0 100 2 SWEEP MONTE 100

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