The PNP transistor at the right side doesn't follow any characteristics of the 4 modes of operation of BJT. How is this possible? PSPICE simulation has shown quite similar results. Here, beta=100.

enter image description here

Picture of schematic

  • \$\begingroup\$ The PNP seems to be in the saturation region. Why do you think that "doesn't follow any characteristics of the 4 modes" ? \$\endgroup\$
    – AJN
    Jul 6, 2021 at 17:33
  • \$\begingroup\$ Only the collector current value is Marked in the diagram. Please mark the emitter and base currents also. Current values marked at the resistor and the voltage source are not the emitter and base currents since there are junction points in between. \$\endgroup\$
    – AJN
    Jul 6, 2021 at 17:35
  • 1
    \$\begingroup\$ The PNP BJT is upside down - the collector and emitter are swapped. \$\endgroup\$
    – jms
    Jul 6, 2021 at 17:37
  • \$\begingroup\$ I have added a picture of the schematic. As it can be seen in the PNP, the emitter current(3.289mA) and collector current(4.552mA) are flowing in the base and their sum is 7.840mA. The base current is flowing out of the PNP, that's why there's a negative sign. \$\endgroup\$
    – M. Fahmin
    Jul 6, 2021 at 17:48
  • 2
    \$\begingroup\$ Replace the PNP with a two diode equivalent circuit and you will see why the current is flowing this way. \$\endgroup\$
    – G36
    Jul 6, 2021 at 18:06

1 Answer 1


First, notice that the PNP transistor base terminal is at \$0V\$ (GND). The collector is pull-up via \$R_2\$ resistor to \$+10V\$. The emitter is also at a higher potential than the base terminal.

So the situation looks like this:


simulate this circuit – Schematic created using CircuitLab


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