Low-frequency noise in permeable base transistors

The predominant noise is
1/f
noise and consists of two parts: a) Noise varying as
I\min{C}\max{2}
, generated mostly with conducting channel and predominating for normal values of the collector voltage V
CE
. b) Noise at low V
CE
and practically independent of V
CE
; it is generated chiefly in the space charge region around the base grating and gives collector
1/f
noise at
V_{CE} = 0
. The turnover frequency of the first noise source lies at about 20 MHz for
V_{CE} = 0.30
V,
V_{BE} = 0.20
V. At sufficiently high frequencies the PBT shows thermal noise of the output conductance
g_{c0}
at zero bias. Generation-recombination noise is observed at large V
BE
and low V
CE
and comes mostly from the space charge region around the base grating.