I am interested in BJT transistor leakage dependency on Vce.

Specifically: parameter ICES (Collector-Emitter Cutoff Leakage, that is, collector/emitter leakage with base shorted to emitter) is generally specified at some large Vce DC bias (e.g. 50V), and I am wondering whether there is an accepted way to extrapolate the specification limits to a lower bias?

Can anyone point me to a published discussion of ICES dependency on Vce? Or BJT performance in the cutoff region in general?

Most references I have seen tend to ignore cutoff leakage characteristics and focus on forward-active and saturation.

  • \$\begingroup\$ Why would you need to know this ? I expect this leakage current to be very dependent on the type/temperature/batch/manufacturer of the transistor. Since the current can vary a lot it is not something to rely on in a circuit design. Have you studied the PN junction in reverse mode because that covers most of this behavior anyway. \$\endgroup\$ – Bimpelrekkie Apr 5 '17 at 12:54
  • \$\begingroup\$ Thanks, that's what I ended up deciding I needed to do: assume the reverse leakage has the same dependencies as PN junction reverse leakage. I was hoping to take advantage of reduced leakage for an application Vce << 50V but decided there would be minimal advantage due to only a weak voltage dependency. Found some papers suggesting a voltage relationship proportional to Vr^(1/n) with n usually ~3 for low voltage reverse bias. \$\endgroup\$ – Sharq Apr 5 '17 at 23:33

The reverse leakage current is fairly constant so there is no extrapolation with Vce above 5V but increases with Ic(max) current rating of device , temperature ( e.g. x10 with 30'C rise )

If you read about basic diode and transistor theory, it explains why. For more info

So your challenge is to consider all the factors in making a selection for low leakage.

When Vbe=0 and Vce= is large, Vbc is a reversed diode, which affects leakage current..

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