Compare BJT with FET

1 Answer

Answer :

FET
BJT
It is unipolar device i.e. current in the device is carried either by electrons or holes
It is bipolar device i.e. current in the device is carried either by both electrons & holes
It is a voltage controlled device i.e. voltage at the gate (or drain) terminal controls amount of current flowing through the device.
It is a current controlled device i.e. the base current controls the amount of collector current.
Its input resistance is very high & is of order of several megaohms.
Its input resistance is very low compared to FET.
It has a negative temperature co-efficient at high current levels. It means that current decreases as temperature increases.
It has a positive temperature coefficient at high current levels. It means that current increases as temperature increases.
It is less noisy.
It is comparatively noisier.
It has relatively lower gain bandwidth product as compared to BJT.
It has relatively higher gain bandwidth product as compared to FET.
It is simpler to fabricate as IC & occupies less space on chip compared to BJT.
It is comparatively difficult to fabricate on IC & occupies more space on chip compared to FET.
It is relatively immune to radiation.
It is susceptible to radiation
It does not suffer from minority- carrier storage effects & therefore has higher switching speeds & cut-off frequencies.
It suffers from minority- carrier storage effects & therefore has lower switching speeds & cut-off frequencies. 

Related questions

Description : Compare between BJT and FET on the basis of (i) Biolar/Unipolar (ii) Tharmal Runaway (iii) Noise (iv) Applications

Last Answer : Parameter BJT FET Bipolar/Unipolar It is bipolar device i.e. current in this device is carried by electrons and holes. It is unipolar device i.e. current ... in oscilloscopes, electronic voltmeters and other measuring and testing equipment because of their high input impedance.

Description : An FET is a better chopper than a BJT because it has (A) lower offset voltage (B) higher series ON resistance (C) lower input current (D) higher input impedance

Last Answer : An FET is a better chopper than a BJT because it has lower offset voltage

Description : What is the difference between BJT and FET?

Last Answer : BJT  is  a  current  opperated   transistor  while  FET   is  a  field   opperated  transistor.

Description : Is the input impedance of MOSFET more than BJT and FET?

Last Answer : Yes, the input impedance of MOSFET more than BJT and FET.

Description : Compare BJT, MOSFET and IGBT .

Last Answer : BJT MOSFET IGBT BJT is a current controlled device. MOSFET is a voltage controlled device. IGBT is a voltage controlled device. The input impedance of BJT is low. ... is minority carrier device. MOSFET is majority carrier device. IGBT is minority carrier device.

Description : Define pinch off voltage and drain resistance of FET.

Last Answer : 1 . Pinch-off Voltage: It is the value of the drain to source voltage VDS at which the drain current ID reaches its constant saturation value. Any further increase in VDS does not have any ... drain to source voltage to the change in drain current. It is also called AC/dynamic drain resistance.

Description : List different types of FET.

Last Answer : Types of FETs:  1. Junction FET (JFET) i. N-Channel JFET ii. P-Channel JFET  2. MOSFET i. E-MOSFET ii. D-MOSFET 

Description : State the application of FET

Last Answer : Applications of FET : * As input amplifiers in oscilloscopes, electronic voltmeters and other measuring and testing equipment because high input impedance reduces loading effect to the minimum. * As Constant ... Used as Analog switch. * As a Voltage Variable Resistor (VVR) in operational amplifiers.

Description : State the need of biasing of BJT.

Last Answer : Need of biasing: The basic need of transistor biasing is to keep the base-emitter (B-E) junction properly forward biased and the collector-emitter (C-E) junction properly reverse biased ... transistor biasing is necessary for normal and proper operation of transistor to be used for amplification. 

Description : Draw circuit diagram of voltage divider biasing list two advantages of voltage divider biasing of BJT.

Last Answer : Two advantages of voltage divider biasing of BJT. 1. It is very simple method of transistor biasing. 2. The biasing conditions can be very easily set. 3. there is no loading of ... 5. The resistor RE introduces a negative feedback. So all the advantages of negative feedback are obtained. 

Description : What is the value of Beta in power BJT?

Last Answer : The beta value in power BJT is 5 to 10.

Description : State 2 advantages of JFET over BJT.

Last Answer : Advantages of JFET over BJT: 1) High input impedance 2) Better thermal stability 3) Produce less noise 4) Smaller than BJT 5) Rugged in construction and simpler to fabricate 6) High degree of isolation between Input and Output. 

Description : List specification of BJT.

Last Answer : * The bipolar junction transistor (BJT) has small signal current gain, α (hfb). * Maximum collector current Ic (max). * Maximum collector to emitter voltage, VCE (max). * Collector to emitter ... . * Collector to emitter cut off voltage, VCEO. * Base emitter saturation voltage, VBE (sat).

Description : State reason BJT is called as bipolar junction transistor.

Last Answer : BJT is called bipolar junction transistor because in BJT current conduction takes place due to majority as well as minority charge carriers.

Description : List configurations of BJT. 

Last Answer : Configurations of BJT : 1) Common Base (CB) configuration 2) Common Emitter (CE) configuration 3) Common Collector (CC) configuration

Description :  If the base current of a BJT is 250 µA and emitter current is 15 mA, then the common base current gain will be A) 0.98 B) 0.41 C) 59 D) 55  

Last Answer :  If the base current of a BJT is 250 µA and emitter current is 15 mA, then the common base current gain will be 0.98 

Description : Which phenomenon is present in thyristors but absent in BJT, MOSFET and IGBT ? (A) forward conduction (B) latching (C) forward blocking (D) reverse breakdown

Last Answer : Which phenomenon is present in thyristors but absent in BJT, MOSFET and IGBT ? (A) forward conduction (B) latching (C) forward blocking (D) reverse breakdown

Description : What is a BJT amplifier?

Last Answer : Bilpolar Juntion transistor , this fuction is control the current

Description : What is a BJT?

Last Answer : Bipolar Junction Transistor (BJT): BJT is a Bipolar device. (Uses both electrons and holes charge carrier for current conduction) Two Junctions (Emitter junction & collector ... mode (Current amplification) Cutoff mode (Open switch) Saturation mode (Close switch)

Description : Explain open emitter BJT drive circuit.

Last Answer : open emitter BJT drive circuit:

Description : Explain the formation of parasitic BJT and parasitic diode in Power MOSFET. Can parasitic diode be used in same power electronics applications?

Last Answer : Parasitic Diode: The parasitic diode is in between drain and source. The MOSFET structure itself contains parasitic diode or body drain diode. This parasitic diode allows the reverse flow of current when the ... of MOSFET as a BJT collector. Parasitic BJT operates in the cut-off region.

Description : Operating frequency of power MOSFET is higher than that of power BJT. Justify the statement.

Last Answer : Power MOSFET have high turning on and turning off capability high switching speed of MOSFET is due to the high rate of change of drain voltage. The switching losses of power MOSFET ... lower frequency. Hence, operating frequency of power MOSFET is higher than that of power BJT.

Last Answer : Yes IGBT is costlier than BJT and MOSFET.

Last Answer : Yes BJT have internal capacitances.

Last Answer : BJT act as switch in saturation and  cutoff region ( ON state in saturation region and OFF state in cut-off region )

Last Answer : In cut-off region of BJT both the emitter-base junction and collector-base junction are reverse biased.

Last Answer : Active region of BJT act as amplifier.

Last Answer : Active , Saturation , Cut-off region of operations in BJT.

Last Answer : Yes BJT have second breakdown problem.

Last Answer : BJT is current controlled device.

Last Answer : BJT have three terminals Base, emitter and collector.

Description : Explain the on state losses in power BJT.

Last Answer : On state losses in power BJT: Transistor have four types of losses one is turn on state losses second is turn off state losses third is turn on switching losses and fourth is turn ... ON = VCE sat x IC With increasing collector current collector to emitter saturation voltage increases.

Last Answer : Because it has a higher switching frequency and heat tolerance.

Last Answer : ON state losses of IGBT is less as compared to MOSFET and BJT.

Last Answer : In  BJT  there  is  movement  of   electrons  and  holes   accros  the  junctions  which  is  basicaly  current  flow.

Last Answer : When Q-point is at cut off region means it is just above the horizontal axis VCE

Last Answer : The proper flow of zero signal collector current and the maintenance of the proper collector emmiter voltage during passage of single called as transistor biasing

Last Answer : Beta is the current gain which is the ratio of collector current to base current.

Last Answer : BJT control the flow of electron so it is a active device.

Last Answer : No, BJT is a current controlled device .

Last Answer : Bipolar junction transistor

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Last Answer : Bjt transistor is a type of transistor which  uses both electrons and hole charge carrier.bjts are used as switches and amplifiers.They amplify currents.

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