Questions tagged [fet]

Field Effect Transistor, a transistor in which most current is carried along a channel whose effective resistance can be controlled by a transverse electric field. Commonly used types of FETs include the Metal Oxide Semiconductor FET (MOSFET), and less common in recent designs, the Junction Gate FET (JFET or JuGFET).

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Help solve rds for pchannel FET from this datasheet

I would like to use a pchannel FET as a voltage controlled resistor in a circuit where my voltages are between 0 and 1.1 Volts. I'm hoping to use the J175 but truthfully I am having a difficult time ...
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Is it possible to make an OFET in a home lab?

Is there a way to build an OFET at home? (low tech, no deep vacuum and plasma, without toxic/hard to dispose chemicals) What can be the minimum budget for that? While conductive polymers are pretty ...
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What is the best way to find an RF FET device for a design?

I'm searching for a jfet or mosfet for a receiver front end, but there doesn't seem to be many options. Everything I find seems to be obsolete. The closest thing I've found to a component that matches ...
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Picking a FET for Logic Level

I've always been confused when picking a FET to be used for logic level signals. There are so many factors to look at for FETs, I get overwhelmed. In this case my supply voltage will be a 3 alkaline ...
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which MOSFET should I use for high voltage inverter circuit

I have an inverter circuit with 2 MOSFETS alternating and a capacitor and couple resistors. When I supply 5V I can see a high frequency square wave, given the capacitor and resistors values. When I ...
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FET: How to understand noise specification?

I was reading an article about electret microphones and there was a link to a datasheet of the FET which was used for impedance matching. It is a popular Fet which is used in many electret microphones....
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2N7000 N-Channel FET switch - resistor calculation for LEDs (design revision 2)

Follow up from a previous post about how to control a 5V supply to LEDs from a 3.3V logic GPIO on a Raspberry Pi Zero W. Most responses recommended that I use a MOSFET / FET instead of a PN2222 ...
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Understanding the role of the FET in this opamp + Zener diode voltage regulator

I'm trying to repair my old audio CD player, and I've found a fault in or around this voltage regulator circuit (it's sourcing VCC for the DAC chip): I understand how the Zener + opamp work to ...
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Mosfet power dissipation in this example

I am trying to design a buck regulator with the following specification: Vin = 24V Vout = 5V I max = 8A Fsw=300k. The load is basically a long strip of RGB LED's. Which in certain cases would be all ...
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Is a cylindrical GAAfet fabricated with lithography and etching?

The GAAfet, aka the surrounding gate transistor (SGT), is basically a FinFET that surrounds the channel on all 4 sides instead of 3. However, a lot of examples show a cylinder instead of a rectangle. ...
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How to use a MOSFET to switch up to its Vds rated specs (e.g. 100 or 150 V)?

So I'm still learning (old dusty ETE degree I finally got around to making use of lately), so be nice please. I get a ton of snark sometimes when I post a question on here. But then there's always one ...
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Are there robust through-hole MOSFETs for beginners?

I want to create switching circuits of less than 20mA in pos/neg 15V applications. 5 to 10 transistors, combination of N and P. Switching at 2.5kHz. I simulated my circuits and now want to solder them ...
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DC Power Relay 12V inrush Current

I have a question regarding 12v dc relay circuit design. About 350mA flows through the relay coil from the 12v power supply, so the pmosfet specification was selected as vds -30v, id -2A class. The ...
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Control of External Power Source with Arduino

Please pardon my ignorance, I'm still trying to wrap my head around this problem. I have built a circuit that will allow me to control distribution of voltage from a single external power supply to ...
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Output voltage in a BS270 circuit

I am reading through Exploring Raspberry Pi and in a section on FETs, there is an example circuit. I understand how the controlled current is calculated $$I = \frac{V}R = (5V)(100\Omega) = 50mA)$$, ...
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BJT vs MOSFET switching speed

I've been reading various answers about the switching speed and frequency of BJTs and MOSFETs, yet I keep finding conflicting answers. Can anyone explain the discrepancy and the real answer? Sources ...
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Are there two sorts of *geometry* of JFET?

In some schematics of JFET, we see in the geometry that the source and drains are perpendicular to the position of the gate. Example : https://en.wikipedia.org/wiki/JFET In some schematics of JFET, ...
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Where can I find the symbolic symbols of various bipolar, JFET, MOSFET in a *unified* style?

Where can I find the symbolic symbols of various bipolar, JFET, MOSFET in a unified style ?
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Why are there no P-channel SiC (silicon-carbide) FETs?

Looking at the top distributors, seems only N-channel power SiC are carried. Why is that?
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MOSFET to drive LED, never turns fully off

I have the following circuit (see attached) where I am using a SI2302 MOSFET to switch an LED using a micro-controller (internal pull down.) The problem I am seeing: Upon switching between 3.3V (HIGH)...
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BSS138 level shifter causing problems

I have encountered a problem that I am unsure how to solve. As shown in the image at the bottom of the question, I have an FPGA (Nexys A7-100T) that generates signal to run a motor connected to a ...
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What exactly does a FET do?

What does a FET actually do? I thought I knew the answer to this question, however upon researching further about the function of a FET I became unsure whether I had the right idea. I thought that ...
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Trailing edge dimmer circuit limitations

I just came across this circuit meant for trailing edge dimming of LED bulbs but I was wondering what else could it be used for and what its limitations are during general use. To my understanding by ...
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How to separate pin when I connect USB?

I'm working on BL653 project, I have an issue how to left VDD_HV pin unconnected when I'm using USB? VDD_HV pin must be unconnected because I am using OPTION 1 with USB. OPTION 1 says that both VDD ...
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4 votes
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High voltage FET or other transistor

What is the highest maximum voltage for a high voltage FET or other transistor? I do not need to be able to buy it, just want to know the voltage it can handle. I was searching the internet and found ...
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How can I reduce the power dissipated across this MOSFET without affecting avalanche?

previous and very relevant question here. I want to reduce or remove entirely the heatsink that is attached to my switching MOSFET. It heats up due to the back-EMF generated by the large inductor that ...
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MESFET in LTSpice

It is really confusing to me. For some reasons I am migrating from Microcap SPICE3 to LTSpice. While in Microcap there was no issue with Statz model for GaAs MESFET, I cant figure out how to ...
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two stage op amp's PSRR

I recently study about two stage amp. In Sedra-Smith, it stays that PSRR for VDD is very small, and ignores this. To understand this, I set Q6's source Vin and Q6 is acting like a common gate ...
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MOSFET terminology seems to vary in every article I read

For someone trying to learn about FETs, it seems there is no consistency in terminology (unless I am reading things wrong.) I am trying to understand the FET as a switch (for power applications.) It ...
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Trying to understand MOSFET Turn on Procedure

I am trying to understand the mosfet turn on procedure. This is from the following application note by TI. https://www.ti.com/lit/ml/slua618a/slua618a.pdf?ts=1613979703351&ref_url=https%253A%252F%...
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Thevenin Equivalent of Common-Gate Amplifier

I'm having some difficulty understanding how Razavi determined \$V_{\text{in, eq}}\$. My understanding was that the small-signal model allows us to model the PMOS device as a constant current source (\...
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Chopper FET as a Preamp

I have a small kit whose schematic is here, it has an LM386 (or equivalent) with an FET preamp stage. The FET went bad, and in searching for a replacement for the now obsolete part, I found that the [...
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Vds meaning in characteristic curve of a MOSFET

As I was wrapping up my design (which didn't include MOSFETs as switches tho, yet), I've realized I wanted to make it crystal clear for myself if I understand the thing correctly. Feels weird, but ...
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Need some help to calculate the resistance in a transistor circuit

I need some help with my transistor circuit. I have this circuit and I'm supposed to find the value for RD and RS, all other values are known. I think I managed to simplify the circuit on the second ...
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Diodes in input protection circuits

I'm studying this protection circuit that protects a microcontroller from inductive transients, switches, and other things in a small aircraft, which would be similar to a car/motorcycle/boat in that ...
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Multiple "typical characteristic" charts in FET datasheet

Looking at following datasheet: https://www.onsemi.com/pub/Collateral/2N5457-D.PDF I'm puzzled as to why there are multiple "typical characteristic " (pairs of) charts. As far as my ...
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Need help in selection of FET for transfer gate

I was studying the variable potentiometer X9C10x series. They are using a series of fixed resistors and some FETs to select points in this series branch. I need one variable point in my circuit. Can ...
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FET source body connected to the same potential

I have learn that the FET looks like this: However industrial FETs are not built like that.The source and the substrate have common potential.However if the source and substrate have common potential ...
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Measuring switching time of 5LN01SP (NMOS)

I am working on switching time test circuit for 5LN01SP specification. This is my circuit: Input test signal is (as per specification) a pulse of 1kHz frequency: PW = 10us D.C. == 1% We can see the ...
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Performing switching time test with NMOS (5LN01SP)

I am about to feed my switching time test circuit with input signal from signal generator. In a 5LN01SP's specification input test signal is marked as: PW = 10us D.C. <= 1% (see the picture) It is ...
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Does the signal direction matter for a series N-channel FET switch circuit?

I'm working with a 40-year old audio circuit that someone modified to use an FET as a series switch. The circuit uses the Toshiba 2SK30A N-channel FET to pass a nominal ±1 VAC audio signal. The Source-...
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Negative drain current in FET

I am new to electronics simulation. I am currently simulating a simple FET where I sweep both the gate and drain voltages. When I plot the drain currents for low values of the drain voltage I obtain ...
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IGBT(Insulated-gate bipolar transistor) Latch-up

What will happen if the Parasitic transistor turn on?
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Self-biased JFET - Midpoint bias: Why set the drain voltage to one-half of it?

To set a midpoint bias, I understand that ID = IDSS/2 (and by equation, VGS = VGS(off)/3.4). For calculating resistor values, why set VD = VDD/2?
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Is this reversed P-MOS next to the battery for some other purpose?

I was handed a schematic with this P-FET next to the battery. My experience tells me that this would not provide any reverse polarity protection (which at a glance it what I thought it was for), but I ...
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High quality, low-noise, pre-amp circuit for condenser microphone (with phantom power)?

EDIT Suggestions so far, and reference to another question indicate that a discrete FET based input stage, perhaps followed by a particular low-noise IC for a second stage, might be a good approach. ...
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BJT transistor max switching frequency vs FET in high frequency computer architecture

Why arent BJTs used with RISC architectures to produce very high speed relatively sparse CPUs? My understanding is that BJTs don't have the forward bias gate capacitance requirements of FETs which is ...
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SOT23 transistor/FET infromation needed

I am trying to Reverse Engineering A PCB but I have problem to identify some PCB components(Highlighted components). I don't know whether these are transistors or FETs. As without knowing their actual ...
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Electret microphone and FET pre-amp

My question is about designing a microphone pre-amplifier that uses an electret microphone. I saw a video of Doug Ford on the EEVBlog, in which he shows some pre-amplifiers for microphones. My ...
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Can you make a CPU out of electronic components drawn by hand on paper?

I explored a lot of literature about paper-based electronics recently, and one particular paper caught my interest: “Handwritten Oxide Electronics on Paper” (DOI: 10.1002/admt.201700009) by Elvira ...
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