Transistors
Transfer Resistor
Chapter 9
, Bipolar Transistors
Collector
Base
Emitter
Two PN junctions joined together
Two types available – NPN and PNP
The regions (from top to bottom) are called the collector (C), the
base (B), and the emitter (E)
, Operation
Begin by reverse biasing the CB junction
Here we are showing an NPN transistor
as an example
Now we apply a small forward bias on
the emitter-base junction
Electrons are pushed into the base, which
then quickly flow to the collector
The result is a large emitter-collector
electron current (conventional current is
C-E) which is maintained by a small E-B
voltage
Some of the electrons pushed into the
base by the forward bias E-B voltage
end up depleting holes in that junction
This would eventually destroy the junction
if we didn’t replenish the holes
The electrons that might do this are
drawn off as a base current
, Currents
Transfer Resistor
Chapter 9
, Bipolar Transistors
Collector
Base
Emitter
Two PN junctions joined together
Two types available – NPN and PNP
The regions (from top to bottom) are called the collector (C), the
base (B), and the emitter (E)
, Operation
Begin by reverse biasing the CB junction
Here we are showing an NPN transistor
as an example
Now we apply a small forward bias on
the emitter-base junction
Electrons are pushed into the base, which
then quickly flow to the collector
The result is a large emitter-collector
electron current (conventional current is
C-E) which is maintained by a small E-B
voltage
Some of the electrons pushed into the
base by the forward bias E-B voltage
end up depleting holes in that junction
This would eventually destroy the junction
if we didn’t replenish the holes
The electrons that might do this are
drawn off as a base current
, Currents
