Transistor biasing means Applying proper voltage and to the transistor to establish it to its proper operating condition. So applying voltage of correct polarity across its two junctions E/B, C/B is really important. Hence, it is worthwhile to remember that for Normal operation:
*Emitter-Base junction is always forward biased. Means current will flow FROM Emitter through Base to Collector.
*Collector-Base junction is always reversed biased. Means current won’t flow From Collector [in case of normal operation only]…
This type of Biasing is known as FR biasing of BJT Transistors.
Important biasing rules
For PNP-transistor, both Collector and Base are negative [N in the middle indicates the Negativity] with respect to the Emitter. Of course, The Collector is more negative than the Base.
Similarly, for NPN-transistor, Collector and Base are positive (P indicates the Positivity) with respect to the Emitter. The collector is more positive than the Base.
Note: We know that current passes from (+) positive to (-) negative. So, for PNP-transistor Current will flow from Emitter through Base to Collector. And for NPN-transistor current will flow from the Collector through Base to Emitter.
The four basic instructions of all transistor circuits
1. Conventional current flow along the arrows whereas electron flow against it.
2. E/B junction is always forward biased.
3. C/B junction is always reverse biased. [mathjax]
4. Emitter current =Base current + Collector current, .
For basic understanding of how transistor works, Its highly recommended to watch this video.
Important Notice: This is worthwhile to remember that for PNP transistor the negative terminal of the battery should always be connected to the Base-N. And for NPN transistor positive terminal of the DC power supply should always be connected to the Base-P. In this case, the other side of the battery connected to the transistor is called Emitter, whose main function is to supply majority charge (either electrons or holes) caries to the Base.
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