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Why is the base voltage of an NPN transistor always positive?
The voltage between the Base and Emitter ( V BE ), is positive at the Base and negative at the Emitter because for an NPN transistor, the Base terminal is always positive with respect to the Emitter. Also the Collector supply voltage is positive with respect to the Emitter ( V CE ).
What is the relationship between base and emitter in NPN?
The voltage between the Base and Emitter ( VBE ), is positive at the Base and negative at the Emitter because for an NPN transistor, the Base terminal is always positive with respect to the Emitter. Also the Collector supply voltage is positive with respect to the Emitter ( VCE ).
What makes a bipolar NPN transistor a good amplifying device?
The value of β can be large up to 200 for standard transistors, and it is this large ratio between Ic and Ib that makes the bipolar NPN transistor a useful amplifying device when used in its active region as Ib provides the input and Ic provides the output. Note that Beta has no units as it is a ratio.
What are the properties of a bipolar junction transistor?
One of the most important properties of the Bipolar Junction Transistor is that a small base current can control a much larger collector current. Consider the following example. A bipolar NPN transistor has a DC current gain, ( Beta) value of 200. Calculate the base current Ib required to switch a resistive load of 4mA.
Is the base of a transistor grounded or grounded?
Even though the base is grounded, there is still a base current flowing because of the negative power supply in the emitter loop, this is similar to what you have. The loop equation would look like:
What should the base of a NPN BJT be?
For an NPN BJT to be in the active region the base must be 0.6-0.7V more positive than the emitter. Since base is grounded the emitter should be around -0.6-0.7V. And that is possible. The emitters can go as much negative as U − + V c e ( s a t) + I o ∗ R e.