Issue link: https://resources.pcb.cadence.com/i/1180526
PSpice User Guide Analog behavioral modeling October 2019 363 Product Version 17.4-2019 © 1999-2019 All Rights Reserved. GLAPLACE EXPR V(%IN+, %IN-) XFORM 1/s The LAPLACE parts use a Laplace transform description. The input to the transform is the value of EXPR, where EXPR follows the same rules as for VALUE expressions (see EVALUE and GVALUE parts on page 356). XFORM is an expression in the Laplace variable, s. It follows the rules for standard expressions as described for VALUE expressions with the addition of the s variable. Note: Voltages, currents, and TIME cannot appear in a Laplace transform. The output of the device depends on the type of analysis being done. For DC and bias point, the output is simply the zero frequency gain times the value of EXPR. The zero frequency gain is the value of XFORM with s = 0. For AC analysis, EXPR is linearized around the bias point (similar to the VALUE parts). The output is then the input times the gain of EXPR times the value of XFORM. The value of XFORM at a frequency is calculated by substituting j·w for s, where w is 2p·frequency. For transient analysis, the value of EXPR is evaluated at each time point. The output is then the convolution of the past values of EXPR with the impulse response of XFORM. These rules follow the standard method of using Laplace transforms. We recommend looking at one or more of the references cited in Frequency-domain device models on page 362 for more information. Example The input to the Laplace transform is the voltage across the input pins, or V(%IN+, %IN-). The EXPR property may be edited to include constants or functions, as with other parts. The transform, 1/(1+.001·s), describes a simple, lossy integrator with a time constant of 1 millisecond. This can be implemented with an RC pair that has a time constant of 1 millisecond. Using the part editor, you would define the XFORM and EXPR properties as follows: XFORM = 1/(1+.001*s) EXPR = V(%IN+, %IN-) The default template remains (appears on one line):