BJT characteristic curves

VI plot of the bipolar junction transistor using labview

I am trying to plot the VI characteristics of the Bipolar Junction transistor using Labview. I have swept the value of the collector emitter voltage. But to fix the value of the base current, I have fixed the base voltage. How to find the value of the base current that is fixed?.

Re: VI plot of the bipolar junction transistor using labview

Hi,

in reality it is no good idea to give a fixed voltage value on BE.

There is a mathematical (exponential) relationship between V_BE and V_CE or I_C, but the influence on temperature makes a real test circuit useless.
A minimal change in temperature may generate a huge change in I_C.

***
Why do you want to create such a VI plot?

Klaus

Re: VI plot of the bipolar junction transistor using labview

Hi,
My aim was to compare the manual as well as the semi automatic ways of performing the device characteristic. My manual readings did not coincide with the simulated readings. The possible error might have occoured while fixing the base current.
Thank you

Re: VI plot of the bipolar junction transistor using labview

Nethrapsgitech said:

I am trying to plot the VI characteristics of the Bipolar Junction transistor using Labview. I have swept the value of the collector emitter voltage. But to fix the value of the base current, I have fixed the base voltage. How to find the value of the base current that is fixed?.

Click to expand...

There exist two different sets for the relationship Ic=f(Vce): (a) for Vbe=const and (b) for Ib=const.

For the second set (with Ib=const) you can use either a current source with different Ib values or a voltage source with a large series resistor between the source and the base input (thus simulating a near-ideal base current source).

Re: VI plot of the bipolar junction transistor using labview

The normal way is to step the base current and sweep the collector voltage for every stepped base current value. This produces the typical DC transfer curves you see in data sheets.

I am trying to get the VI curves of the BC 107 NPN transistor, in common emitter configuration.
I face two issues:
1) Input characteristics :The base current is linearly increasing with the base emitter voltage , which is not the actual case seen in the model graph.(Vce was fixed)
2) Output characteristics: There is no flow of collector current even with increase in the collector emitter voltage.( Base current was fixed to a particular value)
I need some help to rectify the errors. Suggest an alternative method if any.
I am using the circuit connected via bread board.

Show a schematic of your test setup.

Whatever you're forcing the base current with, should
be used to measure current as well (most ATE SMUs
and most parameter analyzer SMUs do this). Failing
that, maybe inline a DMM with useful low current range
and acquire that.

Realize that many higher performing BJTs need fixturing
help, like ferrite beads etc., to kill oscillations that may
corrupt DC readings. The more of a wireball the fixture
is, the more so. Might put a 'scope to the collector
node and satisfy yourself that it's all really DC and
not a transmitter.

If you can't get a direct current reading for the base
due to poverty, consider putting a large series resistor
and using a larger voltage source, do a rough subtract
of Vbe (Ib=(Vbb-Vbe)/Rbb) and maybe it's good enough.
For example a 10V power supply and 10kohms would let
you stuff 1mA of base current which is more than enough
for an integrated transistor (other than, say, power
MOSFET drive final stage - and these would be built of
fingers which could be individually tested).

The 1968 book "Silicon Transistors" from Philips shows the characteristic curves for the old BC107 transistor. I think the more modern BC547 is the same.
Since there is no collector current then as I said on the other website, you burnt out your transistor.