IV Curve Tracer
1. Overview
The current–voltage (IV) tracing algorithm automatically generates a complete IV curve by starting from a defined bias point and progressively stepping through voltage or current values until a specified stop condition is reached. The algorithm calculates intermediate points between these limits to form a smooth, continuous trace.
This approach is particularly useful for regions where the IV curve becomes very steep (for example, during avalanche breakdown). In such cases, a voltage-driven simulation may become unstable and fail to converge.
This algorithm drives one of the device contacts with a variable impedance current source (a voltage source in series with a resistor), this allows the source to look more like a current source on vertical sections of the curve. Using this algorithm it is possible to trace round complete curves that would not ordinarily be possible.
The algorithm uses the number of Newton iterations to control the step size. The IV Trace component is only valid for steady state simulation mode, and a 2D physical device model must also be present in the circuit. An IV trace should be directly connected to a device contact.
2. Parameters
| Name | Description | Unit |
|---|---|---|
Name | A unique name for the component. The checkbox toggles whether this is displayed in the circuit. | - |
Start Voltage | Normally the sweep will start from the origin. If it is desired to solve from some other point then the starting bias must be specified. This may need to be used in conjunction with an appropriate initial solution from a previous run. | V |
Initial Step | Size of the first voltage step in the IV trace. The next step will be taken as half the first and the automatic curve tracing takes over. | V |
Minimum Voltage | Minimum voltage step, if the voltage step falls below this value current stepping is used instead. | V |
Maximum Voltage | Maximum voltage allowed in curve tracing algorithm, when this is reached the solver will stop. | V |
Minimum Current | Minimum current step, if current is below this value voltage stepping will be used. | A |
Maximum Current | Maximum current allowed in curve tracing algorithm, when this is reached the solver will stop. | A |
Minimum Newton | If the number of Newton iterations falls equal to or below this value the step length will be increased. | - |
Maximum Newton | If the number of Newton iterations is greater than this value the step length will be decreased. | - |
Current Increment | A multiplicative factor applied to the current step when the number of Newton iterations is less than or equal to Minimum Newton. | - |
3. Usage Instructions
For instructions on adding a component to the simulation circuit, click here.
Select the curve trace icon 
and drag it into the circuit. Fill in the parameters detailed above and connect it to a device contact with a wire.
The magenta play button in the toolbar will become saturated allowing you to run a curve trace simulation.