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A darlington emitter follower is two transistors operating as one. Both collectors are tied together. The emitter of the first is connected to the base of the second.
The darlington exhibits very high gain. If hFe, for instance, on each transistor was nominally 100, the effective hFe would be nominally 100 squared, or 10000.
The emitter follower is a common collector configuration where the emitter tracks the base, offset by the base-emitter forward junction voltage. In a darlington, there are two junctions in series, so the effective junction voltage is about 1.4V.
Voltage gain of the darlington, like any emitter follower, is one, or unity. Current gain, however, is limited only by the power supply, the transistor, and effective hFe. In the darlington configuration, current gain is effectively considered to be large enough to be thought of as "infinite".
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What is an emitter follower?
This is a particular transistor amplifier configuration. In general, the input signal is applied to the base, the collector is connected to a supply voltage, and the output is taken between the emitter and power supply common. One of the characteristics of the emitter follower is the output voltage "follows" the input, but the output is reduced by the Vbe voltage (the voltage drop between base and emitter, approximately 0.7 V for a silicon bipolar transistor).
What is an darlington array?
An integrated circuit with several darlington transistors on it. Usually they are independent darlingtons.
Why is collector current less than emitter current?
The percentage of doping in emitter is higher than collector region.hence large current is flow to emitter than collector.
Why name of the device is UJT?
UJT means Uni Junction transistor terminals are Emitter,Base1 and Base2.UJT is also called double base diode.UJT operates when the emitter is forward biased.voltage is applied between base1 and base2.If an external voltage is applied at terminal E,no current will flow in to the emitter as long as this applied voltage is less than emitter voltage.When this applied voltage exceeds emitter voltage,current will flow into the emitter and holes get injected from emitter to base1 and are repelled by base2.This results in increase in the region between the junction and the base 1.The increase in conductivity results drop in emitter voltage and increased forward bias of the junction.so emitter current also increases.Then it exhibits a negative resistance.
What is the function of emitter bypass capacitor in common emitter amplifier?
The emitter bypass capacitor in a common emitter amplifier will have less resistance as the frequency increases. Since gain in this configuration is collector resistance divided by emitter resistance (within limits of hFe), the gain will thus increase for higher frequencies, making this into a high pass filter.
What is the advantage of emitter follower?
The advantage of the emitter follower is that it has a positive gain of 1.
What kind of feedback is used in emitter follower?
emitter follower is a type of negative feedback ,
Which transister is used in emitter follower circuit?
A: Any transistor of either polarity can be used as an emitter follower, The purpose of an emitter follower is to provide current to the load since it cannot provide any voltage gain
What are the differences between Emitter follower and source follower?
no difference between emiter follower and source follower
What is the difference between a CB amplifier and CE and emitter-follower?
I think you mean a common emitter amplifier, which is an amplifier of voltage. Emitter-follower or common collector amplifiers are used to match impedances, or to amplify power or current. The emitter-follower is a type of common emitter circuit that has a resistor between the emitter and ground. The output signal is taken from the point between the emitter and its resistor.
What is emitter follower?
A: When a signal is not amplified but simply taken from an emitter the reason is that the emitter will provide better current capabilities
What is the advantage of darlington transistor to an ordinary bipolar junction transistor?
higher current handling / heat dissipation This is not really true as those are not singular characteristics of darlingtons. The major characteristics of a darlington is high gain, typically ranging from over 100 to 1000. And since there are essentially two transistors in the case of a darlington and the base of a darlington is connected to the base of the first transistor whose emitter is connected to the base of the second (power or output) transistor, the forward voltage drop from the base to the emitter of the darlington is approximately 2 times the forward voltage drop of a single transistor. it is a beta multiplier therefore it has higher emitter current capability and it not a hi gain per say just higher current capability as opposed to a regular transistor. usage is for an emitter follower which has no voltgage gain at all.
What is Voltage gain of emitter follower?
The voltage gain of an emitter follower is theoretically 1. In practice, due to losses, it is marginally less than one.
Why emitter follower is used in circuits?
The (Class C, Common Collector) Emitter Follower is used to amplify the available current from a voltage driving circuit that might be disturbed by the load impedance. If the actual voltage value is important, the emitter follower is often teamed up with an opamp which sets the emitter voltage based on the input voltage.
Why common current is called an emitter follower?
It is not called that.
Why collector current is called an emitter follower?
It is not. You have something confused.
Why emitter follower is called so?
Because of the geometry of the common collector configuration, changes in base voltage appear at the emitter. Said another way, what happens at the base pretty much happens at the emitter, and the emitter can be said to "mirror" or "follow" the base. The emitter is a follower of the base, and the name emitter follower appeared and was used.
