When the out from a transistor is the exact replic of the input signal then it is called unmodulated signal i e. there will not be any change in frequency voltage power etc
small signal operations
The saying "at what current is transistor biased" means to ask the current through the transistor when there is no signal present. Typically, a transistor is biased at the center of its linear region, so as to minimize distortion. This, of course, depends on whether or not the transistor is AC or DC coupled, and where the clipping points might be.
In any transistor circuit , there is a phase shift. It takes a finite time for the controlling signal, usually on the base connection, to have an effect on the circuit and cause a change to the output. The shape of the signal remains but it is shifted in time (phase). The difference varies by configuration. It can be as much as180 degrees if the circuit is inverting the signal. The addition of passive components add to the shift.
Transistors are semiconductor devices which can be used as switches (to turn on and off an electrical signal or current path) and also as a signal amplifier in a circuit. There are two broad types of transistors BJT (Bipolar Junction Transistor) and FET (Field Effect Transistors). - Neeraj Sharma A transistor is a silicon device with 3 leads, emiter, collector, and base. It is used both as a fast switching device and for signal amplification. It is said to be "saturated" when maximum current is flowing and "cutoff" when no current is flowing from the emiter to the collector. It takes a difference of approx. .7 volts between the emiter and base to turn it "on". Good switch but actually inferior in sound quality to its predicessor, the "Thermionic" or good ole vacuum tube. If you don't believe me, listen to a guitarist play through both a transistor and vacuum tube guitar amp. You will be quite amazed!!! For signal amplification the input signal goes into the base and the amplified output signal is taken at the collector with the transistor operating, or biased, between cutoff and saturation. It would be normally biased in between cutoff and saturation for the signal to be "linear" or non distorted. The signal at the collector will be inverted (180 phase shift) with respect to the input signal. There are other applications where the output is taken at the emiter where the signal is not inverted (in phase) with respect to the input signal. This configuration, generally, has no gain or has what is called "unity gain". Sometimes you see this when separate stages need to be impedance matched for maximum efficiency. The transistor is first "biased" or configured for a specific amount of gain and the output signal is taken at the collector with a higher amplitude than the input at the base. A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power . It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits . The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Following its development in 1947 by John Bardeen , Walter Brattain , and William Shockley, the transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things. The transistor is on the list of IEEE milestones in electronics, and the inventors were jointly awarded the 1956 Nobel Prize in Physics for their achievement.
A: Feedback is a signal fed back from the output like from collector to the base .
Power transistor can conduct large amount of currents through it, more than small signal transistor. power transistor has a vertical structure and small signal transistor has horizontal structure.In power transistor quasi saturation region is present which is absent in the small signal transistor. In power transistor there is a inculsion of drift layer which is not there in the small signal transistor. Power dissipation is less in power transistor and it is more in small signal transistor. b.v.polytechnic,vasai pushkar vaity.
Yes, a transistor can amplifiy an a.c. signal.
A small signal NPN transistor used for general purpose audio amplifiers and switching.
Transistor=Transfer+Resistor. When Transistor operates in active region its input resistance is high and output resistance is low. So,We can consider transistor as a device which transfers its resistance from high to low. And by this property transistor amplifies input signal.
Transistor increase the strength of a weak signal from the base
A high signal input to a transistor amplifier gives a high signal output provided it stays linear.
The work of a transistor is to amplify the input signal to get high output value.
Transistor is an active element because it can amplify the signal applied.
The PNP transistors conducts when there is no signal at base (0V or grounded), when base current is increased the conduction of PNP transistor decreases.
It depends on how you bias the transistor. If you ground the emitter, which is very common, you will need to offset the input signal so you can amplify the full voltage swing.
Modulation index is also called as Modulation depth. The modulation index of a modulation scheme describes by how much the modulated variable of the carrier signal varies around its unmodulated level.
hie is input impedance when signal applied at its base.