The MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is one of the most widely used transistors in modern electronics. It plays an important role in controlling current and voltage in circuits, and is used in many applications such as switching and amplification. As such, it is essential for professional engineers and technicians to understand the fundamentals of the MOSFET, and to be able to answer MOSFET related questions during an interview. In this blog post, we will discuss some of the most common MOSFET interview questions and look into the answers that will give you the best chance of success in your job interview. We will provide some tips to help you prepare and make a good impression on potential employers. We will also discuss how you can use the knowledge of your MOSFETs to your advantage in order to make educated decisions about relevant topics. By the end of this blog post, you will have a better understanding of MOSFET
- State the full form of MOSFET.
- How many terminals the MOSFET consists of?
- Describe the main advantage of the Power MOSFET over other semiconductor devices.
- Advantages of the MOSFET.
- Whether the MOSFET is voltage controlled or current controlled device? …
- Voltage controlled device.
Interview Question Practice – AMD Interview question on CMOS logic | Everything EE
MOSFETs with short channel lengths can experience short channel effects. Among these consequences are things like a rise in leakage current and a fall in transconductance. On the other hand, long channel effects are effects that happen in MOSFETs with long channel lengths. Among these outcomes are things like heightened resistance and diminished current gain.
The main benefit of MOSFETs is that they turn on with a very low resistance, allowing them to carry a lot of current with very little power loss. They are therefore perfect for use in applications like power amplifiers and others where power efficiency is crucial.
A variety of electronic devices use MOSFETs, a type of transistor. It is crucial to be ready to respond to inquiries about MOSFETs if you are being interviewed for a job that requires working with them. In this article, we’ll go over some typical MOSFET interview queries and offer some advice on how to respond to them.
The insulated gate field effect transistor, or MOSFET, is a variety of transistor that regulates the flow of electrons using an insulated gate. The gate can be used to control the flow of electrons without affecting the rest of the transistor because it is isolated from the rest of the device. Because of this, MOSFETs are excellent choices for use in electronic devices that require precise control over the flow of electrons.
Whether CMOS or NMOS is superior is a question that lacks a clear answer. Each type of MOSFET has its own advantages and disadvantages. Compared to NMOS MOSFETs, CMOS MOSFETs are typically smaller and consume less power. However, NMOS MOSFETs typically operate faster and can carry more current. The ideal MOSFET to use will ultimately depend on the particular application.
Ans:It is the ratio of iD and (vGS – vGS(th)). It controls the clamping voltage level of the gate-source voltage in a MOSFET switching circuit, which affects dvDS/dt during turn-on and turn-off.
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Ans: A device known as a power MOSFET developed from the MOS integrated circuit technology. By redesigning lateral MOSFET to increase their voltage blocking capacity, the first attempts to create high voltage MOSFETs were made. The resulting technology was called lateral double deffused MOS (DMOS). But it soon became clear that using a vertically oriented structure would allow for much higher breakdown voltage and current ratings. Since then, almost all Power MOSFET manufacturers have adopted the vertical DMOS (VDMOS) structure. A power MOSFET using VDMOS technology has a three-layer structure that is vertically oriented and alternately made of p type and n type semiconductors. To create a complete device, many cells are connected in parallel.
A MOSFET, similar to a BJT, has layers of alternating p and n type semiconductors. But unlike BJT, a MOSFET’s p type body region lacks an external electrical connection. A thin layer of SiO2 insulates the gate terminal from the semiconductor. The source metallization shorts the body with an n+ type source. Thus minority carrier injection across the source-body interface is prevented. Due to the electric field created by the gate-source voltage, a high density n type channel forms in the p type body region of a MOSFET, causing it to conduct. The n+ type source and drain regions are connected by this n type channel. Through this channel, current conducts between the drain and the source due to the flow of only electrons (the major carriers). Contrarily, in a BJT, current conduction results from the injection of a minority carrier across the base-emitter junction. Consequently, a BJT is a bipolar device with a minority carrier and a MOSFET is a voltage-controlled majority carrier device.
The “Source” and “Drain” n+ end layers have roughly the same amounts of heavy doping. The body (or substrate), a p type middle layer, has a moderate doping level that is two to three orders of magnitude less than n+ regions on both sides. The n- drain drift region has the lowest doping density. The breakdown voltage of the device is based on the thickness of this region. A thin layer of silicon dioxide, also known as gate oxide, insulates the gate terminal from the semiconductor body and is positioned over the n- and p-type regions of the cell structure. The source and drain terminals of the entire device are created by joining the source and drain regions of all the cells on a wafer to the same metallic contacts. Similarly all gate terminals are also connected together. The source is made up of numerous (thousands) tiny polygonal areas that are encircled by gate regions. The ON state resistance of the MOSFET is similarly influenced by the geometric shape of the source regions. Each MOSFET cell contains a parasitic BJT with its base and emitter shorted by the source metallization, which is an intriguing feature of the alternating n+ n- p n+ structure. The nonzero resistance between the base and emitter of the parasitic npn BJT results from the body spreading resistance of the p type substrate. A lot of care is taken when designing MOSFET cells to minimize this resistance and suppress the switching of the parasitic BJT. In the circuit symbol of a Power MOSFET, the collector-base junction of the BJT is shown as an antiparallel diode (referred to as the body diode) when there is an effective short circuit between the body and the source.
What are the three operating regions of MOSFET?
MOS transistors have three regions of operation:
Interview Question and Answer of MOSFET
Answer-1: MOSFET stands for Metal oxide Semiconductor field effect transistor. a kind of transistor where the control voltage rather than the control current The MOS integrated circuit technology led to the development of the power MOS field effect transistor (MOSFET). Extremely low input power levels are supported, and the switching speed is unrestricted by design.
Question-2. Explain the working of MOSFET?
Answer 2: A special class of field-effect transistor (FET) called a MOSFET operates by electronically varying the width of a channel through which charge carriers move. The wider the channel, the better the device conducts. The source is where the charge carriers enter the channel, and the drain is where they exit. The voltage on the gate electrode, which is physically situated between the source and the drain and is separated from the channel by an incredibly thin layer of metal oxide, determines the channel’s width.
Question-3. How many terminals the MOSFET consists of?
Answer #3: The Source, Drain, and Gate terminals of a MOSFET are its three terminals.
Question-4. What do you mean by the MOSFET’s depletion and enhancement modes?
Answer 4: This is known as the MOSFET’s depletion mode, and it occurs when the negative gate to source voltage is applied. Enhancement mode: The MOSFET’s enhancement mode is when a positive gate to source voltage is applied to an N channel.
Question-5. What are the main application of MOSFET?
Answer 5: Metal oxide semiconductor FET (MOSFET) has a variety of important uses, some of which are listed below. MOSFET is used in electronic devices for signal switching and amplification. It is used as an inverter. It can be used in digital circuit. MOSFET can be used as a high frequency amplifier. It can be used as a passive element e. g. resistor, capacitor and inductor. It can be used in brushless DC motor drive. It can be used in electronic DC relay. It is used in switch mode power supply (SMPS).
Question-6. In which type of MOSFET, there is no physical channel?.
Answer-6: Enhancement MOSFET
Question-7. write down advantages of MOSFET?
Answer-7: The conventional junction FET, or JFET, has some disadvantages that the MOSFET does not. No matter what the gate voltage (as long as it does not become so high that it causes the physical breakdown of the metallic oxide layer), there is no current flowing between the gate and the channel because the gate is electrically isolated from the channel. Thus, the MOSFET has practically infinite impedance . This makes MOSFETs useful for power amplifiers.
Question-8. Where does the MOSFET’s power dissipation rate tend to be the highest?
Answer-8: Active region
Question-9. What three operating regions does a MOS transistor have?
Answer 9: A MOS transistor operates in three different regions: the cut-off region, the non-saturated region, and the saturated region. Cut-off region: Essentially, this is the accumulation mode, where there is no real current flow between the source and drain. The drain current depends on both the gate and drain voltages in the active, linear, or week inversion region, which is the non-saturated region. The drain current is dependent on the gate voltage in the saturated region, which is the strong inversion region, and is independent of the drain-to-source voltage.
Question-10. It’s possible to compare the MOSFET switch’s on-state to?
Answer-10: Capacitor
Question-11. Is the gate voltage maintained during depletion type MOSFET operation?
Answer-11: Negative
Question-12. What is the Power MOSFET’s main advantage over other semi-conductor devices?
Answer 12: Low input power and rapid switching are the main benefits of MOSFETs.
Question-13. In a P-channel MoSFET the substrate is?
Answer-13: N-type
Question-14. What connection is necessary for an N-MOSFET of the enhancement type to work as a resistor?
Answer-14: Gate should be connected to the drain.
Question-15. Describe whether the MOSFET is a current- or voltage-controlled device.
Answer-15: MOSFET is a Voltage controlled device. The input voltage controls the output current of the MOSFET, which is a voltage-controlled majority charge carrier device. Only electrons can conduct current in an n channel MOSFET, whereas holes can only conduct current in a p channel.
Question-16. What is main reason for switching delay in the MOSFET?.
Answer 16: Input and output capacitor charging and discharge in the MOSFET is the primary cause of switching delay.
Frequently Asked Question and Answer on MOSFET
MOSFET Interview Questions and Answers in PDF form Online
FAQ
What are 6 types of MOSFET?
- PMOS Logic. As was already mentioned, when compared to BJTs, the integration of a MOSFET enables high levels of circuit efficiency.
- NMOS Logic. …
- CMOS Logic. …
- Depletion Mode MOSFET Devices. …
- MISFETs. …
- Floating-Gate MOSFETs (FGMOS) …
- Power MOSFETs. …
- DMOS.
Which MOSFET is mostly used?
Automotive electronics frequently employ power MOSFETs, particularly as switching components in electronic control units and as power converters in contemporary electric vehicles. A wide range of applications also use the hybrid MOS-bipolar insulated-gate bipolar transistor (IGBT).
Do MOSFETs use AC or DC?
Semiconductors have polarity, so, power is always DC. Although it’s not a standard use, in some configurations you could wire them in series for AC using the substrate diode. When performing SMPS on AC, you typically install a rectifier and use just one mosfet for both polarities.
What are the 4 terminals of MOSFET?
There are four terminals on each MOSFET: the body (B), source (S), gate (G), and drain (D).
