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When operated in cut off and saturation mode the transistor acts like what?
switch
Current flow in transistor?
A; Must define the transistor type and its mode of application if you expect an answer. It has the capabilities to conduct both way on either type dueing saturation mode. Hope that helps
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.
Why transistors are designed?
For switching applications transistor is biased to operate in the saturation or cutoff region. Transistor in cutoff region will act as an open switching whereas in saturation will act as a closed switch.
How is an transistor used as a amplifier?
Voltage is applied between the collector and emitter. A signal is applied between the base and emitter. The input signal will control how much the transistor turns on and the larger current flowing across the Collector/Emitter will be the same, but larger, than the input. Therefore amplified.To keep the transistor switched on and to prevent the input signal switching it off, the transistor has to be biased on. This is usually done with a network of resistors on the base, raising the voltage to keep it conducting.
When operated in cut off and saturation mode the transistor acts like what?
switch
Current flow in transistor?
A; Must define the transistor type and its mode of application if you expect an answer. It has the capabilities to conduct both way on either type dueing saturation mode. Hope that helps
How can you tell if a transistor is a saturated bipolar transistor?
Saturation mode is the condition wherein the base-collector junction becomes forward biased, as opposed to reverse-biased in the case of active mode. It is necessary for the base-emitter junction to be forward biased, and thus a base current will be flowing. Typically the base current is much higher than it would be in active mode, and the effective Hfe of the transistor drops rapidly. These conditions apply to both NPN and PNP transistors equally. In practice, the collector-emitter voltage of a transistor in saturation is very low, less than 0.1 V, but this depends on the specific transistor. Some high-power transistors will only saturate to 0.4 V. Saturated transistors sometimes begin to overheat or smoke, although saturation is not always a fault condition. When a transistor is used as a switch, this means it alternates exclusively between cutoff and saturation.
What should be the value of collector current in terms of DC gain if transistor is in saturation mode?
DC current gain is collector-emitter current divided by base-emitter current. In linear mode, gain is beta, or hFe. In saturation mode, however, the transistor is over-driven and you can no longer relate collector-emitter current to base-emitter current. The transistor operates like a switch, and collector-emitter current is a function of voltage and load impedance only. (Ignoring the relatively small voltage drop.) To maintain saturation mode, the collector-emitter current must be smaller than the base-emitter current times hFe. Often, it is several times smaller, because hFe can vary from transistor to transistor, and your design must account for this variability.
What is saturation and active region in a transistor?
The output current of a transistor is controlled by the current in the 'base' input: Increasing the control current will increase the output current in a more or less linear fashion. In the saturation region, this is no longer true: The transistor is nearing the limits of how much current it can conduct, so increasing the control current further has little or no effect. When using a transistor as an amplifier, you want to stay away from the saturation region as it would distort the signal you are amplifying. When using a transistor as an on/off switch, as in digital circuits, being in the saturated region is 'on' and a normal mode of operation.
What is the difference between nonlinear devices and linear devices?
In saturation region transistor acts as a non linear device i.e, there is no linear relation between input and output because in saturation region output does not change for variation in input. Whereas in other operating mode transistor acts as a linear device.
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.
Why transistors are designed?
For switching applications transistor is biased to operate in the saturation or cutoff region. Transistor in cutoff region will act as an open switching whereas in saturation will act as a closed switch.
Why biasing a transistor?
We bias transistors in order to determine the modes of operation ( that is whether the transistor is operating in the active cut off or the saturation regions).
How many states does a transistor have?
A transistor can be in three conditions or states. It can be active (at a voltage higher than the emitter), in saturation or cut off (no current).
What transistor can be used in enhancement mode?
MOSFET can be used in enhancement mode
How do you correct the problem when you have to drive two transistors in saturation mode from a single input and one operates properly while the other misbahaves?
Use two resistors to separate the load between the bases of the transistors, thereby limiting the current. What's happening is that the base of one transistor is absorbing most of the current while the other transistor isn't getting its share. If you're driving them into saturation, you only need just enough current to accomplish the task. The excess will just end up being dissipated as heat, which won't be good for the transistor. Time to do the math: operating voltage, minus the base voltage plus .6V (for the emitter/collector junction diode effect), divided by the max base current, equals resistance to drive the transistor into saturation. By limiting the current you help prevent the transistor from going into thermal runaway and destroying itself.
