Transistor ft definition

People had been carrying around music for several years — transistor radios, the Walkman, etc. At the Namegabe home, the transistor radio, charged with batteries, was the property of the men. The transistor is still a critical item in electronics and production isn't up to demand, especially for special designs. The PDP-3 circuitry is the static type using saturating transistor flip-flops and, for the most part, transistor switch elements.

There was a miniature pocket radio—a transistor radio—on top of the short wave cabinet. Keeter seemed to hesitate for a minute, then shrugged his shoulders and dropped the transistor into the general's sweating palm.

The electrical properties of this odd specimen are unusual and interesting and could lead to a new type of transistor. An electronic device that can work as an amplifiertransforming weak electrical signals into strong ones. It is normally made from silicon or other semiconductors.

ft of a MOSFET

Advertisement top definitions quizzes related content examples explore dictionary british scientific cultural transistor. Take this quiz on the Words of the Day from April 6—12 to find out! Words nearby transistor transient modulationtransient synovitistransignificationtransilienttransilluminatetransistortransistorizetransittransit camptransit circletransit instrument.

Words related to transistor camcorderstransistorsboxportable. Example sentences from the Web for transistor People had been carrying around music for several years — transistor radios, the Walkman, etc. Operation Terror William Fitzgerald Jenkins.

Membership Drive Murray F. The Atomic Fingerprint Bernard Keisch. The device is capable of amplification, etc, and has replaced the valve in most circuits since it is much smaller, more robust, and works at a much lower voltage See also junction transistorfield-effect transistor.

An electronic device that controls the flow of an electric current, most often used as an amplifier or switch. Transistors usually consist of three layers of semiconductor material, in which the flow of electric current across the outer layer is regulated by the voltage or current applied at the middle layer.

Having replaced the vacuum tube, transistors are the basis of much modern electronic technology, including the microprocessor. See also logic circuit logic gate. All rights reserved. Test Your Word IQ! Play Now.Hot Threads. Featured Threads. Log in Register. Search titles only. Search Advanced search…. Log in. Contact us.

Close Menu. JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding. Forums Engineering Electrical Engineering. FT in transistor. Does any books tell me moe about designing collpits oscillator with all steps such as choosing transistorCapacitorRelated Electrical Engineering News on Phys. AlephZero Science Advisor.

Homework Helper. Ft is not a "constant", it depends on the transistor's operating point. Last edited by a moderator: May 5, FT depends on operating condition. The data sheet always give the condition on current and all. For me, I would use a higher frequency transistor to do a MHz oscillator.

I don't want the parameters of the transistor to get in the way. Low frequency transistor that has fT of MHz has higher parasitic capacitance and other parameters, those a device dependent and you can't count on it.

transistor ft definition

Get a higher frequency transistors, something like 1GHz and the circuit will behave more like the design Again, this is my way of doing things, I am not claiming it is the best way. I just want to keep things simple by eliminate as much variable as possible and I had been doing this. Last edited: Apr 29, Is Ft of a transistor like the gain-bandwidth product in an opamp?

DragonPetter said:.Remember Me? What is fT of a transistor? A BC wouldn't be used for such applications because of higher capacitances, although it has sufficient gain at this frequencies.

But its still unclear for me. By capacitance, I thinkyou mean the input and output capacitance. Input capacitance for BC was found to be 9pF and I was not able to find the same for BF as it is not specified in the datasheet I referred. Could you please tell me why we should take this capacitance into account even though we require only higher gain. Also please tell me which transistor is good for an FM transmitter circuit 80 to MHz.

For an RF amplifier, particularly the feedback capacity Ccb is a critical parameter. Because of the higher capacitance, BC is less suited as an RF amplifier, that's the whole story.

You shouldn't operate the transistor in frequencies near ft. Similar Threads Replacement for 2N transistor 8. Asymmetric Transistor Vs Symmetric Transistor 2. How HFE varies from transistor to transistor? Difference between SP transistor and package transistor 8. Part and Inventory Search.

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Recently Updated Groups. Top Experience Points. EE World Online. Design Fast. The time now is See also bipolar transistor and transistor. A field-effect transistor FET is a type of transistor commonly used for weak-signal amplification for example, for amplifying wireless signals.

The device can amplify analog or digital signals. It can also switch DC or function as an oscillator. In the FET, current flows along a semiconductor path called the channel.

At one end of the channel, there is an electrode called the source. At the other end of the channel, there is an electrode called the drain. The physical diameter of the channel is fixed, but its effective electrical diameter can be varied by the application of a voltage to a control electrode called the gate. The conductivity of the FET depends, at any given instant in time, on the electrical diameter of the channel.

A small change in gate voltage can cause a large variation in the current from the source to the drain. This is how the FET amplifies signals. Field-effect transistors exist in two major classifications. The junction FET has a channel consisting of N-type semiconductor N-channel or P-type semiconductor P-channel material; the gate is made of the opposite semiconductor type. In P-type material, electric charges are carried mainly in the form of electron deficiencies called holes.

In N-type material, the charge carriers are primarily electrons. In a JFET, the junction is the boundary between the channel and the gate. Normally, this P-N junction is reverse-biased a DC voltage is applied to it so that no current flows between the channel and the gate. However, under some conditions there is a small current through the junction during part of the input signal cycle.

The gate electrode is a piece of metal whose surface is oxidized. The oxide layer electrically insulates the gate from the channel. Because the oxide layer acts as a dielectric, there is essentially never any current between the gate and the channel during any part of the signal cycle.

Special precautions are necessary when handling or transporting MOS devices.A transistor is an electronic component used in a circuit to control a large amount of current or voltage with a small amount of voltage or current. This means that it can be used to amplify or switch rectify electrical signals or power, allowing it to be used in a wide array of electronic devices.

It does so by sandwiching one semiconductor between two other semiconductors. Because the current is transferred across a material that normally has high resistance i. Patents for the concept of a transistor date as far back as in Germany, though they seem to have never been built, or at least no one ever claimed to have built them.

What is TRANSISTOR? What does TRANSISTOR mean? TRANSISTOR meaning, definition & explanation

The three physicists received the Nobel Prize in Physics for this work. There are essentially two basic types of point-contact transistors, the npn transistor and the pnp transistor, where the n and p stand for negative and positive, respectively.

The only difference between the two is the arrangement of bias voltages. To understand how a transistor works, you have to understand how semiconductors react to an electric potential. Some semiconductors will be n -type, or negative, which means that free electrons in the material drift from a negative electrode of, say, a battery it's connected to toward the positive. Other semiconductors will be p -type, in which case the electrons fill "holes" in the atomic electron shells, meaning that it behaves as if a positive particle is moving from the positive electrode to the negative electrode.

The type is determined by the atomic structure of the specific semiconductor material. Now, consider an npn transistor.

Each end of the transistor is an n -type semiconductor material and between them is a p -type semiconductor material. If you picture such a device plugged into a battery, you'll see how the transistor works:. By varying the potential in each region, then, you can drastically affect the rate of electron flow across the transistor. Compared to the vacuum tubes that were used previously, the transistor was an amazing advance. Smaller in size, the transistor could easily be manufactured cheaply in large quantities.

transistor ft definition

They had various operational advantages, as well, which are too numerous to mention here. Some consider the transistor to be the greatest single invention of the 20th century since it opened so much in the way of other electronic advancements. Virtually every modern electronic device has a transistor as one of its primary active components.


Because they are the building blocks of microchips, computer, phones, and other devices couldn't exist without transistors. There are a wide variety of transistor types that have been developed since Here's a list not necessarily exhaustive of various types of transistors:. Edited by Anne Marie Helmenstine, Ph. Share Flipboard Email.These have been designed to fulfil a variety of different applications in all areas of electronics. In order to define the parameters of a transistor there are many different specifications that are used.

Each of these transistor specifications define an aspect of the performance of the transistor. Transistor manufacturers issue specification sheets for their transistors which are typically found on the Internet, although years ago engineers used to study data books to find out the information.

For electronic circuit design, selecting the right transistor will need several of the transistor parameters to match the requirements for the circuit. Therefore a variety of the parameters will need to be carefully matched. Not all the parameters are electrical - aspects such as the size of the package, and whether the device is a surface mount transistor, i.

With most PCB assembly now using surface mount technology to aid the automated electronics manufacturing of products and equipment, most transistors manufactured these days are SMD transistors. Whilst most transistors made these days are SMD transistors because of the automated PCB assembly techniques used, there are still many leaded devices as well.

Specific transistor part numbers are normally available as leaded versions and also for SMD transistors with the same electrical specifications, although aspects like the heat dissipation will differ because of the different package styles. There are a number of standard parameters with abbreviations that are used to define the performance of a transistor.

The definitions of these parameters are outlined in the table below:. The main type of material used for semiconductor devices is silicon. Although other materials like germanium and gallium arsenide are available, silicon is the most popular because it is cheaper to process and in addition to this, the processes are more advanced than for other materials.

As it is used for many other semiconductor devices, there are many benefits of scale and technology available. Silicon offers good overall performance with a base emitter junction turn on voltage of around 0. It is the maximum collector base voltage - again it is generally measured with the emitter left open circuit.

This value should not be exceeded in the operation of the circuit. This parameter is important because some leakage current will flow between collector and base, causing the part to heat up. Alternatively excessive voltage can damage the collector base junction.

As terminal damage can occur to the bipolar transistor, this rating should not be exceeded and ideally the transistor should be run with a good margin in hand. In operation the collector-base junction is reverse biassed, and a small reverse current will flow I CBO. As the reverse voltage is increased the electric field in the depletion region of the collector base junction increases, and the reverse current starts to rise as minority carriers gain sufficient energy to generate hole electron pairs which then increase the reverse current.

Eventually avalanche breakdown occurs. This limits the maximum voltage that can be applied to the transistor. V CBO is typically higher than V CEO because with the base terminal of the BJT open, any leakage current will also be the same as externally applied base current, and this is amplified by the transistor. This transistor specification is the maximum voltage that can be placed from the collector to the emitter. It is normally measured with the base open circuit - hence the letter "O" in the abbreviation.Semiconductor processes often quote figure of merit, Ft and Fmax.

What are they? We believe that Fmax is a better measure of a transistor's capability compared to FT, does anyone want to weigh in on this? Fmax is the frequency where unilateral gain U becomes unity, or zero dB. It is still one of the most important figures of merit for a transistor, especially at microwave frequencies. This is a pretty sporty device even by today's standards, possibly an HBT from a boutique foundry such as Teledyne. Except we just faked the data. At millimeter-wave frequencies, you can come close to realizing all that gain, and maybe get 10 dB from an amplifier stage at GHz.

There is a ton of gain down at classical microwave frequencies, but you will probably never achieve that in a real design when you look at stabilizing it.

More on this later Now let's look at U on a log-freq scale. How do you calculate values in between? Here is the formula:. You can expect to achieve maybe 10 dB in a narrow-band one-stage design with such a device, matched for small signal gain at 96 GHz, allowing 2 dB or so for input and output matching network losses.

transistor ft definition

We hope to add a calculator on this one of these days: type in F, Fmax and U will be revealed We'll add to this later. FT is the "transition frequency" where current gain goes to unity zero dB. Toggle navigation Menu. Filter by alphabets Filter by categories. FMax Fmax is the frequency where unilateral gain U becomes unity, or zero dB. References S.

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