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Questions tagged [mosfet]

An transconductance (using voltage to control current) electronic component used for switching and amplification. Acronym for Metal-Oxide-Semiconductor Field-Effect Transistor. (from http://en.wikipedia.org/wiki/Transistor)

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Mazzilli flyback driver mosfets keep failing

I've been trying to build a high voltage generator consisting of a high-voltage transformer and a Cockroft-Walton multiplier. I have actually tried several different drivers to drive a high-voltage ...
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137 views

How to identify SMD device marked LEFBV?

I have a SOT23-3 component marked \$\underline{\textrm{L}}\,\underline{\textrm{E}}\,\overline{\textrm{F}}\,\overline{\textrm{B}}\,\textrm{V}\$ as shown in the following images: The following ...
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3k views

Dual active bridge converter

I'm having issues calculating the power losses associated with the operation of a bidirectional isolated Dual Active Bridge DC/DC converter. The converter is controlled using Phase Shift Modulation (...
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30 views

MOSFET pinchoff reduce current

I understand that in an n channel MOSFET as Vgs increases, electrons are attracted towards the gate forming an n channel. These electrons are responsible for the conduction of the MOSFET. As Vds ...
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166 views

Gate of a transistor and mosfet damaged

In my schematic, I found that the base of transistor Q7 (2n2222) was damaged. I tried to replace it with a BS170 MOSFET, and the same thing happened where the gate was damaged. The microcontroller ...
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52 views

MOSFET switching on

I have a doubt. Consider an N-MOSFET: which is the voltage that can switch on it? The voltage between Gate and? Sometimes I read "between Gate and Bulk", sometimes "between Gate and Source", sometimes ...
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48 views

Calculate the junction temperature of a MOSFET during pulse

Hi all I have a question regarding using a MOSFET for a constant current source. I have found this question with some answers but it wasn't clear to me yet. I want to create a constant current LED ...
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157 views

Large negative current spike in N-Channel MOSFET source when turn-off

I am working on repairing a power supply board of a LCD TV (200W power), more specifically, the PFC section (active power factor correction). See schematic (adapted from here): I've replaced some ...
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47 views

Can I generate following voltage waveform with single PWM FET?

I am designing power supply which must output following voltages at a maximum of 1.5 A stepped down from a 24 V DC supply. 24 V 13-15 V 0-5 V Waveform for one of the inputs requires following ...
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44 views

Controlling IRL2703 with 3.3V (Reading MOSFET datasheets)

I have an application where I want to switch on/off a resistive load (24V/300mA) from a 3.3V MCU GPIO pin at a rate of 1 HZ or slower. I also have some IRL2703 MOSFETs, and I wonder if they would do ...
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53 views

Questions about a remote relay control application with a MOSFET

I need to control eight solenoid-valves for water drainage outdoors, remotely and simultaneously. The valves are normally closed (NC) type which I guess, in that context, means they open and let the ...
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158 views

High Voltage Cascode with MOSFET LT Spice Simulation

I'm an electronics engineering student and want to develop a high voltage switch with normal Si N-MOSFETs. After some research, I discovered cascode switches for this application. Most of these ...
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104 views

Inverter Design - High Side MOSFET - Slow Switch Time

I've posted previously on a similar issue which can be found here Overview: My design is a 3 phase inverter with: MOSFETS are STF10N60DM2 Gate Driver is 6EDL04N06PT I'm using only a single high ...
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140 views

How does a cascode current mirror maintain equal Vds of the bottom transistors?

A basic current mirror is shown below: The load and reference current relationship is affected by channel length modulation: In order to cancel the effects of channel length modulation, vds1 and ...
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63 views

NMOS bidirectional variable resistor: How to increase body diode barrier potential?

I want to use an NMOS as a variable input resistor to an inverting amplifier. The source is connected to virtual ground and the drain is connected to the input. I need to accomodate both positive and ...
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How does a MOSFET conduct in saturation region?

It is a simple question but I could not find a straightforward answer. When a MOSFET enters saturation region, the channel length starts to decrease, and the channel width is the smallest near the ...
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108 views

Measuring battery voltage, capacitor on drain (nMOSFET switching load)

I've got a schematic to measure a battery voltage using a nMosfet (triggered by a GPIO high level). The voltage is measured at the Probe (see picture). Can you tell me the purpose of Capacitor C1 on ...
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251 views

Adding a ferrite bead to source of mosfet (smps)

We are designing a SMPS (ultra low noise) based on TI schematics http://www.ti.com/lit/df/tidrgc2/tidrgc2.pdf (5V, 15W quasi resonant) In order to reduce EMI (we have some ringing across Mosfet when ...
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153 views

Load Sharing/Isolation Circuit with ADP5063

I'm designing the battery power/charging circuit for the Reform DIY laptop which uses a (big) LiFePo4 cell. For the charger IC I've now settled on ADP5063 as it seems simple and can charge with 1.5A ...
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165 views

What MOSFET circuit replaces a diode in a 48V 40A escooter?

I want to use a 1kW generator and convert my eScooter to a hybrid. The scooter uses a 48V SLA battery bank of 4x22Ah SLA batteries in series. I used a transformer from a 1200W microwave oven and ...
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317 views

Conduction angle in three-phase rectifier

In a standard three-phase bridge rectifier, which consists of 6 diodes, each diode (or thyristor) conducts 120º of the full 360º period. I have built a synchronous rectifier (for research purposes), ...
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Input selection circuitry for USB/battery

I'm making a development board, and trying to sort out the input selection circuitry, where if a battery (3.7V lipo) and USB is connected at the same time, it doesn't damage the circuitry, by stopping ...
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146 views

Protection High side Mosfet driver with less solenoid connection

I suggest control solenoid. Solenoid will be connected externally via a connector. Steering is via high side MOSFET driver. The requirements are for detecting disconnection, short circuit and current ...
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2k views

How to use MOSFET in avalanche mode?

I'm thinking of a very simple circuit to generate high voltage pulses, like this: simulate this circuit – Schematic created using CircuitLab The MOSFET in this case will turn on until the ...
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772 views

Calculating signal attenuation for AC?

So we've got this; simulate this circuit – Schematic created using CircuitLab Which I've been told is equivalent to the sum of it's Coutputs to an AC signal; simulate this circuit So then; $...
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2k views

Level shifting with BSS138 - weird values

I need to connect 5V and 3.3V devices via I2C as follows: I've connected 3.3V and 5V pull-ups and tried to measure the voltage. There is 5V on HV and TX_HV but 4,7V on LV / TX_LV. Putting TX to LOW ...
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BeagleBone Black Driving NFETs w/GPIO

In short, I want to drive some NFETs directly from some of the BBB's GPIO. 3 of the NFETs will pass 1-3 Amps of D-S current and 1 NFET will pass <1 Amp from the D-S. As you may know the BBB's ...
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29 views

MOSFET Choosing For SPWM Inverter

I'm trying to build a 220V spwm inverter with 30kHz carrier freq. with 350V input and 7A output current. I'm trying to choose suitable mosfet but I'm very confused about dv/dt, reverse recovery(body ...
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MOSFET current mirror with compensation

I am trying to understand the difference between a MOSFET current mirror with and without compensation (Replace Q3 with a short circuit). In the case of a current mirror without compensation, V1 ...
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47 views

What is maximum symmetrical output voltage swing in this case?

I'm pretty new to Electronics and hence the following doubt. I could not understand how the authors reasoned out the swing limits for this problem ((b)-part only)
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79 views

WS2811 LED Strip Driver

I'm in the process of designing a LED strip driver using a WS2811 chip and 3 MOSFETs. I've attached the schematic below. I based it on the reference circuit in the WS2811 datasheet (link), and this ...
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57 views

I'm an undergrad building a railgun and I need assistance!

I am a physics undergrad that chose his senior project to build a low voltage railgun, however I am running into a few different issues. 1.) The paper mentions a "flyback diode bank" which I have ...
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57 views

Simple push-pull problem

I've made a circuit based on the schematics below, which works fine at simulation. The goal is to add some extra oomph on the output of a LT1210 opa (V1) to drive a piezo element at higher voltages ...
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85 views

Finding Width of MOSFET

We are struggling with part iv of the question above where we have to find the width of both MOSFETS. As you can see from our working out, we have found a width of 2 meters for the nMOS, which we know ...
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34 views

Dual-gate mosfet gate resistance at DC

I'm investigating a bf1105 dual-gate mosfet for use in an rf mixer circuit. I've never used a dg mosfet before so I decided to do a DC sweep of the gates to determine an appropriate bias point. I ...
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Mosfet Vgs-Qg graph

What is the reason behind the horizontal region in the center? why gate-source voltage doesn't increase in that region, even though we are adding charges to it?
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44 views

mosfet as a switch on arduino pin and xbee explorer board 5v

I have looked at various examples of MOSFET switches but I am not knowledgeable enough to adapt what I see to what I would like.... I want to have a pin on my 5 volt Arduino Micro board turn on or off ...
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42 views

Why does my GPIO only show 2V when connected to the Gate Termina lof NTE2390?

I've got a circuit set up with a motor that matches this diagram. When a 3 V power supply is connected to the Gate terminal, the motor spins. However, when I replace the 3V supply at the Gate ...
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44 views

ngspice .measure syntax in AC + par()

Why do the two netlists give totally different output impedance values ? Netlist 1: ...
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110 views

How to isolate a RLC circuit with MOSFET switches?

I'd like to isolate, with high-side and low-side switches, a RLC circuit after the inductor has been energized with a current of 2-3A from a 12V source (see sketch). When the RLC circuit is isolated ...
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74 views

Parallel MOSFET Circuit Analysis

I'm solving part b of this question I started with the assumption that both MOSFETs were in saturation mode to simplify calculations, I then solved for the circuit, tested the assumption using vds, ...
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110 views

MOSFET Driver P-channel

I want to create a DC-chopper to drive a motor. I found the following schematic online: However i don't understand how the MOSFETs are driven. On top there is a P-channel MOSFET with source connected ...
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59 views

1.8 V to 5.0 V level shifter with low delay and low rise time

i have a problem with finding the right components and circuit for the following problem. I have a device that is producing trigger signals with a length of 100 ns at a amplitude of 1.8 V (left part ...
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237 views

Overvoltage protection circuitry choice

I need to design a input overvoltage protection for a 45W DC-DC converter rated for a 9-24V wall wart input (so, 45W / 9V = 5A input current at max). So far I've seen two approaches (schematics below):...
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37 views

Choosing a suitable FET for a design project

I'm currently working on a project to produce a high speed and high voltage pulse. I'm trying to find a suitable FET. I intended to supply a voltage of about 50v to circuit. And using the FET to go ...
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32 views

Mosfet Based impulse voltage generator

enter image description here **Details- Mosfet_1 will turn on for 20ms and charge the capacitor C2 and after that, it will turn off. Then the Mosfet_2 will turn on for 3ms with 40kHz frequency and ...
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114 views

Howcome there is current flowing through the gate of this transistor?

I have a few conceptual questions: If there wasn't Rg (Resistor between gate and drain), would Vin = Vout then? For small signal analysis, current can flow through the gate (AC) if there's a voltage ...
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129 views

switching between two similar power sources - solar battery and cr2032

I'm trying to create a circuit powered by two alternative power sources. The first one is a Li-Po battery charged by a solar panel and the second one - standard 3v battery, ie. CR2032. The circuit ...
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58 views

Maximum mid-band gain of s.s. model MOSFET amplifier?

Schematics I need to find the maximum possible gain for this NMOS cascode circuit. Here is the s.s. model: Work I used nodal-matrix analysis (basis is KCL) to find the gain (\$A_v\$): $$ \...
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221 views

Why is the transconductance of a BJT greater than that of a MOSFET?

During my classroom lectures, I came across this doubt of why the transconductance (\$g_m\$) of a BJT is greater than that of a MOSFET, i.e.: $$g_{m(BJT)} > g_{m(MOSFET)}$$ It would be very ...