In electronics, the Gummel plot is the combined plot of the base and collector electric currents,
I
c
and
I
b
, of a bipolar transistor vs. the base-emitter voltage,
V
b
e
, on a semi-logarithmic scale. This plot is very useful in device characterization because it reflects on the quality of the emitter-base junction while the base-collector bias,
V
b
c
, is kept at a constant.
A number of other device parameters can be garnered either quantitatively or qualitatively directly from the Gummel plot:
the common-emitter current gain,
β
, and the common-base current gain,
α
base and collector ideality factors,
n
series resistances and leakage currents.
Sometimes the DC current gain,
β
, is plotted on the same figure as well.
