Justify. Power MOSFET is operated at high enough gate source voltage to minimize the conduction losses. 

1 Answer

Answer :

MOSFET is metal oxide field effect transistor. MOSFET is a voltage controlled device. MOSFET is majority carrier device. MOSFET are of two one is n-channel MOSFET and p-channel MOSFET. Gate, drain, and source are the three terminals of MOSFET. The current flows from drain to source when the voltage is applied between gate to the source terminal. The current between gate to source is very small. The active region, cutoff region, and ohmic region are the three regions in MOSFET. MOSFET goes in an ohmic region when the gate to source voltage is larger and drain to source voltage is small.

image


The ohmic region is also called as triode region. In the ohmic region, the MOSFET behaves like a small voltage controlled resistor. In the ohmic region, power dissipation is kept low by minimizing drain to source voltage even if the drain to source voltage is fairly large. Hence, power MOSFET is operated at high enough gate-source voltage to minimize the conduction losses.

Related questions

Description : Explain MOSFET gate drive circuit and totem pole configuration.

Last Answer : MOSFET gate drive circuit: The turning on and turning off of MOSFET can be controlled from gate to source voltage signal. If the gate to source voltage of MOSFET exceeds threshold ... this configuration, the two switches (transistors) are used in totem pole arrangement with a comparator.

Description : Find power delivered by voltage source

Last Answer : Find power delivered by voltage source

Description :  An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when A) ZL = R B) ZL = jXS C) ZL = R-jXS D) ZL = R+jXS 

Last Answer :  An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when ZL = R-jXS

Description : In voltage source converter based HVDC transmission system the active power is controlled by changing (A) phase angle of the converter ac input voltage (B) supply frequency of the converter ac input voltage (C) magnitude of the converter ac input voltage (D) DC voltage at the inverter terminals

Last Answer : In voltage source converter based HVDC transmission system the active power is controlled by changing phase angle of the converter ac input voltage

Description : The threshold voltage of an n- channel enhancement mode MOSFET is 0.5V when the device is biased at a gate voltage of 3V. Pinch off would be occurs at a drain voltage of (A) 1.5V (B) 2.5V (C) 3.5V (D) 4.5V

Last Answer : The threshold voltage of an n- channel enhancement mode MOSFET is 0.5V when the device is biased at a gate voltage of 3V. Pinch off would be occurs at a drain voltage of 2.5V

Last Answer : already answered here is mosfet current controlled device?

Description : Draw the structural diagram of GTO. Explain briefly the switching behavior of GTO with the help of appropriate voltage and current waveform.

Last Answer : Gate Turn Off Thyristor (GTO) Conventional Thyristor can be turned on with gate terminal but can not turn off from gate terminal. But in case of Gate Turn Off Thyristor (GTO), we can turn it on and off ... subdivided as storage period (Ts), fall period (Tp) and tail period (Tt).

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.

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

Description : A 3-phase voltage source inverter operates in 180° conduction mode with a star connected resistive load. If input dc voltage is 100 V, then the peak to peak output line voltage is :

Last Answer : A 3-phase voltage source inverter operates in 180° conduction mode with a star connected resistive load. If input dc voltage is 100 V, then the peak to peak output line voltage is : 200 V

Description : A voltage source inverter will have better performance if its  (1) load inductance is small and source inductance is large.  (2) both load and source inductance are small.  (3) both load and source inductances are large.  (4) load inductance is large and source inductance is small. 

Last Answer : A voltage source inverter will have better performance if its load inductance is large and source inductance is small. 

Description : A voltage source inverter is normally employed when  (1) source inductance is large and load inductance is small (2) source inductance is small and load inductance is large (3) both source and load inductance are small (4) both source and load inductance are large

Last Answer : 3

Description : What is Voltage Source Inverter (VSI) ?

Last Answer : Voltage Source Inverter (VSI)  Inverter is device which converts Direct Current (DC) to Alternating Current (AC). There are two types of inverters one is Voltage source inverter ... VSI consist of two load terminals and three phase VSI consist of three load terminals.

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.

Description : A certain power MOSFET has a maximum junction temperature specification of 1500o C, a junction-to-case thermal resistance of 1.00 C/W, and a junction-to ambient thermal resistance of 600 C/W. If the ambient temperature is 300o C ... the device will be A) 1.52 W B) 1.72 W C) 1.92W D) 2.00 W

Last Answer : A certain power MOSFET has a maximum junction temperature specification of 1500o C, a junction-to-case thermal resistance of 1.00 C/W, and a junction-to ambient thermal resistance of  ... 300o C, then the maximum allowable power dissipation in the device will be 2.00 W 

Last Answer : MOSFET have high current losses due to High on state resistance. Hence MOSFET is used for low power applications.

Description : Justify the statement. Antiparallel diode is connected across MOSFET.

Last Answer : In MOSFET current is flow from drain to source but when the load is inductive the current may flow in opposite direction. To avoid the opposite flow of current and to protect MOSFET the antiparallel diode is connected across MOSFET.

Description : Nodal Analysis with Voltage Sources dependent voltage source and two supernode

Last Answer : Nodal Analysis with Voltage Sources dependent voltage source and two supernode

Description : Nodal analysis example with voltage source and supernode

Last Answer : Nodal analysis example with voltage source and supernode

Description : Source transformation Replace the circuit with voltage source in series with a single resistor

Last Answer : Source transformation Replace the circuit with voltage source in series with a single resistor

Description : A current controlled voltage source is equivalent to :  (A) series voltage feed -back amplifier (B) shunt current feed -back amplifier (C) shunt voltage feed -back amplifier (D) series current feed -back amplifier

Last Answer : A current controlled voltage source is equivalent to : shunt voltage feed -back amplifier

Description : A DC voltage source is connected across a series RLC circuit. Under steady-state conditions, the applied DC voltage drops entirely across the

Last Answer : A DC voltage source is connected across a series RLC circuit. Under steady-state conditions, the applied DC voltage drops entirely across the C only

Description : Which of the following theorems enables a number of voltage (or current) source to be combined directly into a single voltage (or current) source. (1) compensation theorem (2) reciprocity theorem (3) superposition theorem (4) Millman's theorem

Last Answer : Which of the following theorems enables a number of voltage (or current) source to be combined directly into a single voltage (or current) source. (1) compensation theorem (2) reciprocity theorem (3) superposition theorem (4) Millman's theorem

Description : A network that consists of at least a voltage source or current source is called A) Active network B) Ideal network C) Sourced network D) Outsourced network

Last Answer : A network that consists of at least a voltage source or current source is called Active network

Description : Consider a circuit with four resistors in series connected to a voltage source. What happens to the voltage across each resistor, if the value of each of the resistors is doubled? A) It will double B) It will remain the same C) It will be halved D) It will become zero

Last Answer : Consider a circuit with four resistors in series connected to a voltage source. What happens to the voltage across each resistor, if the value of each of the resistors is doubled? A) It will double B) It will remain the same C) It will be halved D) It will become zero

Description : The internal resistances of an ideal current source, and an ideal voltage source are, respectively, (A) 0, ∞ (B) ∞, ∞ (C) ∞, 0 (D) 0,0

Last Answer : The internal resistances of an ideal current source, and an ideal voltage source are, respectively, ∞, 0

Description : An ideal voltage source has?

Last Answer : An ideal voltage source has zero internal resistance.

Description : For a voltage source?

Last Answer : For a voltage source terminal voltage cannot be higher than source e.m.f.

Description : An ideal voltage source should have?

Last Answer : An ideal voltage source should have zero source resistance.

Description : what is ideal voltage source?

Last Answer : every voltage source have their own resistance that is called as internal resistance it is because of the resistance of electrodes and electrolytes in the battery interms of other supplyit have ... in universe it means ideal voltage source is this voltage source having internal resistance zero

Last Answer : MOSFET provides better efficiency at high frequency and its high speed switching losses are less hence MOSFET is used for high frequency.

Description : Two resistances Rl and Ri are connected in series across the voltage source where Rl>Ri. The largest drop will be across?

Last Answer : Two resistances Rl and Ri are connected in series across the voltage source where Rl>Ri. The largest drop will be across Rl.

Description : Describe with neat sketch the construction and working principle of MOSFET.

Last Answer : Construction and working principle of MOSFET:  A) Depletion type MOSFET: Construction: The N-channel depletion type MOSFET is formed on P-type silicon substrate with two heavily ... accumulation of electrons and hence more current. Thus the MOSFET is a gate voltage controlled device.

Description : State the applications of MOSFET

Last Answer : Applications of MOSFET: i) Switching-mode-power-supplies (SMPS) and linear power supplies. ii) Brushless DC motor drives iii) Solid state DC relay iv) Automobile applications v) Stepper motor controller vi) Lighting controls vii) Solenoid drivers viii) Robotics ix) Induction heating

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 : parallel operation of MOSFET can be done more easily as compared to thyristor. why?

Last Answer : Parallel operation of MOSFET can be done more easily as compared to thyristor because the resistance of MOSFET is increases with increase in temperature. MOSFET have the positive temperature coefficient. In ... the parallel operation of MOSFET can be done more easily as compared to the thyristor.

Description : Explain difference between enhancement MOSFET and depletion type MOSFET.

Last Answer : In enhancement MOSFET channel is not initially exists but in depletion MOSFET channel is already exists. In case of depletion MOSFET if the voltage is applied between drain and source the drain current will flow ... a channel. depletion MOSFET & enhancement MOSFET

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 : Explain the series and parallel operation of MOSFET. Which is suitable and why?

Last Answer : Series operation of MOSFET: To increase voltage handling capability MOSFETs are connected in series. When the MOSFETs are connected in series each MOSFET should turn on and turn off ... on and turn off time and transconductance. Each MOSFET should share current equally.  

Description : What is depletion type MOSFET?..........

Last Answer : Depletion MOSFET: Depletion MOSFET is a MOSFET in which the channel already exists. If we apply a voltage between drain and source then the drain current will flow even if the gate to source ... in figure. The drain current will be reduced as the gate to source voltage made more negative.

Description : What is enhancement MOSFET?...............

Last Answer : Enhancement MOSFET: There are two types of MOSFET one is enhancement MOSFET and second is depletion MOSFET. In enhancement MOSFET channel is created by applying threshold voltage between gate and source ... mode. The enhancement MOSFET will not conduct if the gate to source voltage is zero.

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

Last Answer : No, MOSFET is not the curent controlled device. The current between drain and source which is drain current is controlled by applying a voltage between gate and source hence MOSFET is a voltage controlled device. 

Description : Explain thyristor gate drive circuit.

Last Answer : Thyristor Gate Drive Circuit: The thyristor can be turned on by pulse voltage signal at gate terminal and it does not require continuous drive signal like the transistor. The gate ... circuit provide required minimum gate voltage and gate current then the thyristor conducts properly.

Description : basic gate drive circuit of GTO

Last Answer : basic gate drive circuit of GTO

Last Answer : MOSFET  are voltage controlled devices.

Last Answer : The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to extinguish the arc.

Description : Why high voltage can reduce power loss?

Last Answer : when voltage has increased due to reduced current flow, thus power loss given by ( I^2R) will be low due to reduced current(I^2) provided that resistance (R) is constant.

Description : Why high voltage is used in power transmission?

Last Answer : The primary reason that power is transmitted at high voltages is to increase efficiency. ... The lower current that accompanies high voltage transmissionreduces resistance in the conductors aselectricity flows ... This means that thin, light-weight wires can beused in long-distance transmission.

Last Answer : Yes MOSFET can operate at very high frequency.