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Why emitter base junction is always forward biased for normal operation of transistor?
The easy answer - it's not always forward biased. Both it, and the collector-base junction, must be forward biased to pass current through to the collector. Whether NPN or PNP the relative bias (voltage) on the base determines the conduction from emitter to collector. NPN: if the base is positive, relative to the collector and emmiter, the transistor conducts. PNP: if the base is negative, relative to the collector and emmitter, it conducts.
For either transistor arrangement, draw two diodes connected either by their anodes or by their cathodes. The base is the region between them. In an NPN, a positive voltage on the anode, compared the to the cathode(s), will forward bias both, allowing current to flow. The same applies to a PNP with a relative negative voltage being the 'switch', turning both on.
bob
02/07/2009
The first paragraph is incorrect. The collector-base junction will be reverse biased for normal operation. The only time an NPN base will be biased more positively than the collector is when it's operating in saturation mode.
The second paragraph is also misleading. It implies that current flows (for NPN) from the collector to the base and then from the base to the emitter. Emitter current is base current plus collector current. The collector-base junction is normally reverse biased, so little current would flow.
Here's a link with relevant info: http://www.nationmaster.com/encyclopedia/Bipolar-junction-transistors
Dennis
What else can I help you with?
Why a transistor can be operated in active region?
a transistor can only work in active region cox in active region collector base junction is in reverse bias and emitter base junction is in forward bias.
How must the two transistor junction be biased proper transistor amplifier operation?
A: Actually it is only one transistor required for amplification the other junction can be a diode. As current Begin to flow it causes a bias across one junction which is opposite biasing for the other, A good differential amplifier will have those junction virtually at the same point with a very good current source because any mismatched will cause and output without any input. It is called voltage offset on the other end if the feedback current is very small it will also produce an output voltage offset known as current offset or basically errors
What is the result of carrier motion of forward biased junction of an NPN transistor?
In a forward-biased NPN transistor junction, electrons from the n-type emitter are injected into the p-type base, where they recombine with holes. This movement of charge carriers creates a flow of current from the emitter to the collector. As a result, a small input current at the base controls a larger output current flowing from the collector to the emitter, allowing the transistor to amplify signals. The overall effect is that the transistor can effectively switch or amplify electrical signals.
When the forward saturation in Bipolar junction transistor occurs?
Forward saturation in a BJT occurs when the ratio of collecter-emitter current and base-emitter current reaches hFe or dc beta. A that point, the BJT is no longer operating in linear mode.
What is the voltage across collector to emitter when transistor is in cut off region?
In the cut-off region of a transistor, the base-emitter junction is not forward-biased, meaning the transistor is effectively turned off. As a result, no current flows from collector to emitter, and the voltage across the collector to emitter (V_CE) is approximately equal to the supply voltage (V_CC) connected to the collector. Therefore, V_CE is at its maximum value, close to V_CC, indicating that the transistor is not conducting.
What is the biasing technique in transistor for it to be in active region?
For a transistor to be in active region : Base Emitter junction should be forward biased and Emitter collector junction should be reverse biased.
A transistor is in active region when?
a transistor in active region when emitter junction is forward biased nd collector junction is reverse biased
How do you know if a transistor is a PNP or an NPN?
To know if a transistor is PNP or an NPN,the following should be verified:For a PNP transistor, the base-collector junction is forward biased while the base-emitter junction is reversed biased.For an NPN transistor, the base-emitter junction is forward biased while the base -collector junction is reversed biased.
How should the two transistor junctions be biased for proper transistor amplifier operation?
Emitter-Base junction should be forward biased.Collector-Base junction should be reverse biased.
A PNP transistor is connected in a circuit so that the collector-base junction remains reverse biased and the emitter-base junction is forward biased This transistor can be used as a power amplifier?
Yes1
Why a transistor can be operated in active region?
a transistor can only work in active region cox in active region collector base junction is in reverse bias and emitter base junction is in forward bias.
What bias conditions must be present for the normal operation of a transistor ampilifier?
Assuming you mean a bipolar junction transistor (BJT): 1. Reverse bias on the collector-base junction. 2. Forward bias on the base-emitter junction, that is 3. Sufficient to give the correct operating point of collector voltage/collector current.
How must the two transistor junction be biased proper transistor amplifier operation?
A: Actually it is only one transistor required for amplification the other junction can be a diode. As current Begin to flow it causes a bias across one junction which is opposite biasing for the other, A good differential amplifier will have those junction virtually at the same point with a very good current source because any mismatched will cause and output without any input. It is called voltage offset on the other end if the feedback current is very small it will also produce an output voltage offset known as current offset or basically errors
What is the result of carrier motion of forward biased junction of an NPN transistor?
In a forward-biased NPN transistor junction, electrons from the n-type emitter are injected into the p-type base, where they recombine with holes. This movement of charge carriers creates a flow of current from the emitter to the collector. As a result, a small input current at the base controls a larger output current flowing from the collector to the emitter, allowing the transistor to amplify signals. The overall effect is that the transistor can effectively switch or amplify electrical signals.
How do NPN bipolar junction transistors turn on and off?
In order to bias a bipolar junction transistor on, you need to forward bias the base-emitter junction at the same time you forward bias the collector-emitter junction, and the ratio of collector current over base current must be somewhat less than hFe, the transistor's gain. This is known as saturated, or non-linear mode, operation. In practice, we drive the base much harder than the calculated required current, so as to minimize dependency on varying hFe's for various transistors.Turning the transistor off is a simple matter of eliminating the base current.In the case of the NPN transistor, the base and collector would need to be more positive than the emitter. In the case of the PNP, they would need to be more negative.
When the forward saturation in Bipolar junction transistor occurs?
Forward saturation in a BJT occurs when the ratio of collecter-emitter current and base-emitter current reaches hFe or dc beta. A that point, the BJT is no longer operating in linear mode.
What is the voltage across collector to emitter when transistor is in cut off region?
In the cut-off region of a transistor, the base-emitter junction is not forward-biased, meaning the transistor is effectively turned off. As a result, no current flows from collector to emitter, and the voltage across the collector to emitter (V_CE) is approximately equal to the supply voltage (V_CC) connected to the collector. Therefore, V_CE is at its maximum value, close to V_CC, indicating that the transistor is not conducting.
