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I have done a “parametric sweep” of the DC voltage source VCC ranging from 0 to 30 V and on the current source with values of iB = 0,50,100,150,200, and 250 µA.

NPN BJT

Below is the plot iC vs vCE (vCE being the X axis). The X axis shows only values from 0 to 10 V.

iv plot

Why is there only 5 lines on the plot if I have swept iB for 6 values?

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  • \$\begingroup\$ As a sanity check you could plot Ib and ensure you are getting 6 sweeps \$\endgroup\$
    – sstobbe
    Commented Oct 27, 2019 at 23:35
  • \$\begingroup\$ why do you show only 4 step currents in 1 unlabelled plot? for an unidentified setup? \$\endgroup\$
    – D.A.S.
    Commented Oct 27, 2019 at 23:53
  • \$\begingroup\$ You say you plotted 6, you ask why you only see 5, I see 4. What's R_C and Beta? \$\endgroup\$
    – StainlessSteelRat
    Commented Oct 27, 2019 at 23:57
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    \$\begingroup\$ @StainlessSteelRat I believe the 5th (and maybe 6th, I need to do the math) is displayed as cutoff. \$\endgroup\$
    – user103380
    Commented Oct 28, 2019 at 2:49

1 Answer 1

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I plotted Ib as a sanity check and got 5 values, so I added 300uA to the sweep. This gave me six sweeps with 250uA included.

This is the the iv plot with Ib. iv plot w/ Ib

This is the the iv plot with Ic. iv plot with Ic

The fact that there is one fewer curve than expected is just an issue with OrCAD. I did a DC Sweep w/ secondary sweep (the primary was for Vcc) with initial point I=0.1uA (since we cannot start from exactly 0), ending point of 300uA and increments of 50uA.

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