How does transistor work as an amplifier?

A transistor acts as an amplifier by raising the strength of a weak signal. The DC bias voltage applied to the emitter base junction, makes it remain in forward biased condition. This forward bias is maintained regardless of the polarity of the signal.

How can a transistor be used as an amplifier or a switch?

The transistor will operate as an amplifier or other linear circuit if the transistor is biased into the linear region. The transistor can be used as a switch if biased in the saturation and cut-off regions. This allows current to flow (or not) in other parts of a circuit.

How transistor works as an amplifier Quora?

Transistors work by amplifying the current supplied at a bipolar junction terminal called the base. A small current applied through the base to another terminal called the emitter will cause a proportionally larger current to flow through a terminal called the collector to emitter.

Where is an transistor used as an amplifier?

A transistor is used as an amplifier in common-emitter (CE) configuration. In this configuration, base-emitter junction is forward biased and collector-base junction is reverse biased.

How does the transistor work?

A transistor consists of two PN diodes connected back to back. It has three terminals namely emitter, base and collector. The basic idea behind a transistor is that it lets you control the flow of current through one channel by varying the intensity of a much smaller current that's flowing through a second channel.

The transistor as an amplifier (Part 1)

How does transistor work as a switch?

With a zero signal applied to the Base of the transistor it turns “OFF” acting like an open switch and zero collector current flows. With a positive signal applied to the Base of the transistor it turns “ON” acting like a closed switch and maximum circuit current flows through the device.

What is difference between transistor and amplifier?

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. Amplifier is a device that increases the Amplitude of a signal.

How transistor works Quora?

When voltage is applied to transistor, the emitter supplies electrons, which is pulled by the base from the emitter as it is more positive than the emitter. This movement of electrons from emitter to collector creates a flow of electricity through the transistor.

How does current flow through a transistor?

NPN transistors let the current flow from the emitter to the collector and base controls the flow of current through it. While PNP transistors are designed to pass the current from the collector to the emitter.

When an NPN transistor is used as an amplifier?

When NPN transistor is used as an amplifier, majority charge carrier electrons of N-type emitter move from emitter to base and then base to collector.

What is the application of transistor?

Transistors are used in our day to day lives in many forms which we are aware of as amplifiers and switching apparatus. As amplifiers, they are being used in various oscillators, modulators, detectors and nearly in any circuit in order to perform a function. In a digital circuit, transistors are used as switches.

What is the input impedance of transistor?

Since the transistors have a constant current source in the emitter circuit, the input impedance is very high. A typical op amp will have an input impedance in excess of 1 megohm with several megohms being reasonable.

Why do amplifier circuits need negative feedback?

Negative feedback reduces gain of the amplifier. It also reduce distortion, noise and instability. This feedback increases bandwidth and improves input and output impedances. Due to these advantages, the negative feedback is frequently used in amplifiers.

In which of the transistor amplifier the voltage gain is highest?

the power gain is highest in Common emitter: This transistor configuration is probably the most widely used.

Why transistor is called current amplification device?

Reason behind it is that it has low output resistance and thus higher current gain is achieved. Current amplification factor for a transistor, which shows by how much times a current given at the input is increased at the output. It clearly indicates that transistor is a current amplification device.

When transistor is used as an amplifier it increases frequency?

So, Transistor to be used as an amplifier, Emitter-base junction must be reverse biased, Collector-base junction must be forward biased. Hence the correct answer is option 1.

Which transistor is best for amplifier?

Why do we need transistors?

Transistors make excellent electronic switches. They can turn currents on and off billions of times per second. Digital computers use transistors as a basic mechanism for storing and moving data.

How is a transistor connected in a circuit?

To connect the transistor as a switch in a circuit, we connect the output of the device that will switch on the transistor to the base of the transistor. The emitter will connect to ground of the circuit. And the collector will connect to the load that the transistor will turn on and the supply voltage of the circuit.

How can a transistor be used as a diode?

Originally Answered: How do I use a transistor as a diode in a circuit? Short the collector to the base. Use the base-emitter junction as a low-leakage diode. The reverse breakdown voltage is very low and the forward current is not spectacular but otherwise, it makes a very good diode.

Can a transistor increase voltage?

A transistor can amplify current, or voltage, or both, depending on how it is configured in the circuit. A bipolar transistor configured as 'Common Collector' amplifies current, but not voltage. When configured as 'Common Base' it amplifies voltage, but not current. In 'Common Emitter' mode it can amplify both.

Can a transistor amplify DC?

Yes, transistors amplify DC. However, DC can only be amplified by BJT and not a FET. The input DC is amplified to the base, and this amplified current is extracted by at the collector.

Which is the best transistor configuration for amplifier and why?

Common emitter transistor configuration

This provides a good overall performance and as such it is often the most widely used configuration. As can be seen from the diagram, in this transistor configuration, the emitter electrode is common to both input and output circuits.

How much power does a transistor use?

Power dissipation:

The power dissipated in the transistor is the voltage drop across the collector emitter junction times the collector current (neglecting the base current times the 0.75V base emitter drop). In the linear range this could be something like 6V@100mA = 600mW (a lot for a little transistor).