Best Answer

Bipolar transistor current gain is also called "Beta," or the h-parameter "hfe."

beta = current_out / current_in

The beta of a BJT is mostly determined by the thickness of the Base region, and by the excess doping in the Emitter relative to the Base. A thin Base and a heavily-doped Emitter leads to a high value for current gain.

In a BJT, beta = Ic / Ib In a FET, beta is usually taken as infinity, since no current flows in or out of the gate. Beta is an impirical number. It means nothing unless the Ic is known or the load. It can have a beta from 1000 to 10 it all depends on the load.

User Avatar

Wiki User

โˆ™ 2009-09-01 22:45:52
This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: How do you calculate the current gain of a transistor?
Write your answer...
Related questions

How do you calculate transistor gain?

The ratio between the output current and input current or ratio between the output current and input voltage is measure of transistor gain

How do you calculate the current gain of a transistor JFET?

FETs don't have current gain as no current flows through the gate. The gain of a FET is a voltage gain and is called mu.

Why CE transistor is preferred over CB?

CE - voltage gain, current gainCB - voltage gain, no current gainCC - no voltage gain, current gain

What is composite transistor?

A Darlington transistor is a composite transistor. The definition is a combination of two or more transistors that have the purpose of increasing the current gain.

What is the voltage gain and current gain for a voltage follower?

In a voltage follower, voltage gain is 1, with an offset of VB-E, and current gain is hFe, limited, of course, by the available current in the supply and by the rating of the transistor.

What is the voltage gain of the 2n2222 amplifier?

A: The gain of a transistor is not linear and even that varies from component to component. The gain can vary greatly depending on the Ic current and the load. Manufactures only give out a typical gain for a particular current. As a rule the lower the Ic current the higher the gain. To really find out what a particular transistor characteristics are a tektronik curve tracer is used.

Which configuration of bipolar junction transistor which will give both current gain and voltage gain?

1. In Bipolar Junction transistors, the type of configuration which will give both voltage gain and current gain is ?

Can a transistor be used as an amplifier?

A transistor can be used as an amplifier because the electrons in the base are multiplied by a gain factor to give the collector current.

What is the difference between a transistor used as a switch and an amplifier?

A transistor used as a switch is operated in saturated mode, where the ratio of base-emitter current over collector-emitter current is far more than hFe, or beta gain. The transistor is either fully on or fully off in this mode. A transistor used as an amplifier is operated in linear mode, where the ratio of base-emitter current over collector-emitter current is equal to or less than hFe, or beta gain. The transistor is partially on in this mode, and is operating as a current controlled current sink.

What transistor amplifier circuit configuration provides both voltage and current gain?

The differential amplifier circuit configuration provides both voltage and current gain.

What is the current gain value of BC 148 transistor?

The hFe (current gain) on the BC148 ranges from a minimum value of 20 to 100, depending on collector current, with a maximum value of 300.

Use of beta in transistor?

Beta is current gain of that transistor,whatever be the input the trasistor. we will get the output multiplied by the beta. for example in CE amplifer if Base current is 10 microampere and beta of that transistor is 100 then collector current would be 1mA i.e. 100 times greater than input current

What is DC load line of a transistor?

A: A transistor has voltage gain as base current is allow to flow. If the load is constant then a DC mirror azimuth path can be plotted as a function of base current and collector current and that is the load line

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.

Why does a CE amplifier have a high gain?

GAIN is a function of load current but basically a small current in the base will make a big change of collector current therefore making a transistor a voltage amplifier as opposed to a current amplifier

What is the alpha beta teta of a bipolar junction transistor?

alpha is the common base current gain = Ic/Ie.beta is the common emitter current gain = Ic/Ib.

Why base current is less than collector current?

Because the transistor has gain. IBE/ICE = min(hFe, RC/RE)

What are the instruments for the study of the gain of a two stage RC Coupled transistor amplifier?

depends on whether you would like calculate or measured results. if you want calculated resulted, then your best bet would be to use an oscilloscope. if you want calculated results, then there are formulas for finding out the voltage, current, impedance, and individual results from each component using the capacitive reactance, voltage, and type of transistor. are you using a summing transistor, inverting amplifying transistor, amplifying transistor, or a different transistor? also are you using DC or AC voltage or current? you need to tell me what type of transistor you are using?

What is darlington configuaration?

A Darlington pair uses two transistors connected to behave as a single transistor with a very high current gain (beta). Transistor-1 has its collector connected to the collector of transistor-2. Transistor-1 has its emitter connected to the base of transistor-2. The base of transistor-1 with the emitter and collector of transistor-2 is used as a single transistor.

How transistor amplify voltage?

Transistors, at least the typical bi-junction transistor, actually amplify current. We set them up in a voltage divider circuit that converts current gain into voltage gain. The simple explanation is that a small delta current on base-emitter causes a larger delta current on collector-emitter. The gain is either hFe or collector resistance divided by emitter resistance, whichever is less.

A NPN transistor connected in common base mode has a current gain of 0.98 if it is now connected in common emitter mode what is the current gain?

The current gain in CE mode called as beta (ß) Tha current gain in CB mode called as alpha (A) ß= A/(1-A) =0.98/(1-0.98) =49 the current gain is 49 in CE mode

How much gain does a good transistor usually have?

A: A transistor has non linear gain. To find the gain a Q point must be specified

What type of transistor is a current controlled current source?

All BJT transistors are. You have the base input current and collector output current with a gain factor. FETs are voltage controlled resistances.

Active region in transistor?

The active region of a transistor is when the transistor has sufficient base current to turn the transistor on and for a larger current to flow from emitter to collector. This is the region where the transistor is on and fully operating.

What is the use of transistor in water level indicator?

It is used to amplify the current. The common-emiiter amplifier is designed so that a small change in voltage (Vin) changes the small current through the base of the transistor; the transistor's current amplification combined with the properties of the circuit mean that small swings in Vin produce large changes in Vout. Various configurations of single transistor amplifier are possible, with some providing current gain, some voltage gain, and some both.