Changing Device Parameters in PSpice Device Model: Diode

PSpice Simplest diode model in PSpice uses only the ideal diode equation More complex diode models in PSpice include: Parasitic resistances to account for the linear regions Breakdown voltage with current multipliers to map the knee between Io and the current at breakdown Temperature dependences of various parameters Parasitic capacitances to account for the frequency dependence 2

PSpice Device Simulation packages Capture Schematics The calculations performed will be identical when using the same device models. The GUIs are not the same. There are minor differences in how the programs interprets some changes that you make to the device models. 3

PSpice Schematics

To plot the I-V characteristics of the diode in PSpice, I run a DC sweep on this very simple circuit. 5

Device Parameters *** Power Diode *** Type of Diode .MODEL D1N4002-X D Part Number ( IS=14.11E-9 Reverse Saturation Current N=1.984 Ideality Factor RS=33.89E-3 Forward Series Resistance IKF=94.81 High-Level Injection Knee Current in Forward Bias XTI=3 Temperature Dependence of Reverse Saturation Current EG=1.110 Energy Bandgap of Si CJO=51.17E-12 Junction Capacitance at Zero Applied Bias M=.2762 Grading Coefficient Inversely Proportional to Zener Resistance VJ=.3905 Turn-on Voltage FC=.5 Coefficient Associated with Forward Bias Capacitance ISR=100.0E-12 Reverse Saturation Current During Reverse Bias NR=2 Ideality Factor During Reverse Bias BV=100.1 Breakdown Voltage IBV=10 Current at Breakdown Voltage TT=4.761E-6 ) Transit Time of Carriers Across p-n Juntion

PSpice Capture

Editing Device Model The device parameters can be changed, but will only be changes for the file that you are currently working on. In Schematics, the changes only apply to the specific part that you had highlighted when you made the changes. In Capture, the changes apply to all components in the file that share the same part model. To simulate the Ideal Diode Equation, you can delete the other parameters or set them to zero or a very large number, depending on what would be appropriate to remove their effect from the simulation