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Loop Gain: LoopGain


This measurement calculates linear loop gain at the intrinsic controlling node (of the drain-source or collector-emitter current) of a nonlinear transistor model in the loop. After bias calculations, when the operating points of nonlinear elements have been determined, the controlling input of the intrinsic current source is disconnected, and the voltage loop gain from that input to the node from which it was disconnected is determined.


Name Type Range
Data Source Name Subcircuit 1 to 1000 ports
Measurement Component String N/A
Sweep Freq (FDOC) List of options N/A


The Measurement Component must be an internal branch of a transistor, which you select by clicking the browse button (the ellipsis to the right of the option). After selecting the top level Data Source Name, use the browse button to navigate to the desired transistor, select it, and use the panel at left to select the ...@ds or ...@ce branch of that transistor. See “Loop Gain” for more information about how loop gain is measured.

All measurements will have additional parameters that allow you to specify the plotting configuration for swept parameters. These parameters are dynamic; they change based upon which data source is selected. See “Swept Parameter Analysis ” for details on configuring these parameters.


This measurement returns a complex value. The complex measurement can be displayed as a real value by specifying the magnitude, angle, real or imaginary component in the Add/Modify Measurement dialog box. Select the dB check box to display the absolute value of the real component in dB.

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