Questions tagged [nmos]

A n-channel metal-oxide semiconductor (nMOS) transistor has n-type carriers in the channel. A positive voltage on the gate turns inverts the substrate (PWell) creating the channel and turning the device on. The term may also be used to describe logic circuits built around nMOS transistors.

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30 views

Simulation doubt with Zener diode & MOSFET

I have the below circuit in which I am trying to perform simulations. Simulation Tool used - Falstad Simulator 12V Zener Diode Top MOSFET Bottom MOSFET Question 1 : The Zener diode is 12V Rated. I ...
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49 views

Switch individual MOSFETs connected across lithium-ion cell for passive balancing

I am working on a passive cell balancing circuit using N-MOSFET. The cell voltage will be monitored by the micro-controller and it can also generate corresponding logic level signal according to over ...
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44 views

I would like to know if the circuit is correct?

simulate this circuit – Schematic created using CircuitLab I have used the voltage follower concept in order to keep the output logic non-inverted.I would like to know the issues that I might ...
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168 views

Why it is preferred to use PNP and PMOS for pull-up, and use NPN and NMOS for pull-down

I have noticed that when I was designing universal logic gates like CMOS NOR gate that uses PMOS for pull-up and NMOS for pull-down. Then I faced it for second time with the H-bridge circuit, but ...
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200 views

Is the current, Ids, through a MOSFET truly 0 when in the cutoff region?

I was testing a circuit using this circuit simulator and found that the nMOS transistor had a current of a few nanoamps running through it when it was in the "off" state. This was unexpected because I ...
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Understanding the working of a NAND GATE using NMOS Transistors

I'm having incredible difficulties understanding how the "Switching Behaviour" (not sure if that's the correct English translation- in German it is "Schaltverhalten") for NMOS and PMOS transistors ...
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39 views

Deriving the NOT logic gate using PMOS logic

I recently started learning about Field Effect Transistors (FET's) and about the MOS circuit family. From my understanding NMOS is made from a p-type substrate and n-type source/drain, whereas the ...
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51 views

Why does this N-channel MOSFET not turn off?

I was playing around on CircuitLab to see if I can add an overvoltage cutoff to the reverse voltage protection circuit in TIs slva139. Using a zener, I expect OVS to start rising beyond the zener ...
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How do I design a RC phase shift oscillator using opamp with the help of cmos (pmos and nmos)?

Designing the opamp using cmos (pmos and nmos) to construct RC phase shift oscillator using opamp with the help of opamp (constructed using cmos.)
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High side mosfet- Extra pulse on turn off

I am making a 3 phase motor drive H-bridge using N channel mosfets (IRFB3607) and BJT based custom mosfet driver such that my turn on and turn off time is about 200ns. Right now I am testing the ...
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Do I really need the N-MOS driver here?

In this circuit I am wondering if I really need the n-channel mosfet to control my dual p-channel MOSFET. I think I can drive this straight from the micro. Just want to second opinion before I modify ...
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98 views

Can a N-channel MOSFET used as a highside switch

Hello I would like to add a high side switch for my circuit. Typically a physical switch can do this job but due to form factor restraints the switches that are rated for my application does not meet ...
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219 views

Improving dV/dt turn-on immunity of a mosfet without increasing turn-off time

I'm designing a solid state battery disconnect switch and I want to improve the mosfets' turn-on immunity (high dV/dt on Vds) without impacting the turn-off time. I don't really care about the turn-on ...
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Difference between transfer gate and NMOS switch in CMOS image sensors

I would like to know the difference between the transfer gate (TX) which is used in 4T CMOS Active Pixel Sensor (APS) as mentioned in the below image and a normal NMOS switch. As far as I know, the ...
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87 views

Bi-directional electronic switch for external circuitry

I am in the process of designing a PCB that is powered by a 10V / 1mA supply from a fandeck (incorporating EC/DC fan motors). One of the functionalities include having continuity between 2 pins on ...
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28 views

MOS circuit for RC circuit power

I am currently working on a circuit where we read the time it takes for a capacitor to charge depending on the load. I would like to know what is the purpose of the first stage with Q1 and Q2. I also ...
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What is the resulting Voltage Transfer characteristics of the modified CMOS-inverter circuit if NMOS and PMOS are interchanged?

What is the resulting Voltage Transfer characteristics of the modified CMOS-inverter circuit, if the positions of \$NMOS\$ and \$PMOS\$ are interchanged?
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Should you not go above max VGS for a Nmos?

I wanted to switch a relay with a raspberry zero, which uses 3.3v, after looking at my 16 years old electronic engineering notes (I'm in IT now), I moderatly re-understood how nmos works (controlled ...
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189 views

Why does nMOSFET keeps blowing up?

I have designed a Boost PFC circuit, But upon switch on transistor is getting blown up and fuse is burnt. So I removed transistor and just connected source to ground. the circuit worked fine. Then I ...
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Rs and Rd in series in MOSFET circuit?

Can we consider Rs and Rd to be in series? That is, is the equation ID = (Vdd)/(Rd+Rs) correct? What is confusing me is that they have the same current, but there's a voltage drop across the drain-...
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42 views

2 NMOS in series, connected source to source

I am working with DC2418A evaluation board (Link to datasheet is HERE) Schematic is on page 5 I am using version A, so we ignore Q1 My question is about Q2 and Q3: Why are they connected source to ...
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6T SRAM write operation calculations

C: Cut off , L: Linear , S : Saturation [keep in mind I am teaching this to myself ahead of time] I understand how to go about finding desired ratio (W/L) for read operation. In the image, M1 would ...
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48 views

Can ground and voltage terminals be connected by a wire?

Helo, I am working on an assignment for a circuit analysis class. I have always been a bit fuzzy about the following: Can I assume that the two top terminals are the same node, the two ground ...
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Is it possible to implement a high-side current mirror with only NMOS FETs?

I need to implement a difference amplifier only using NMOS technology. I am struggling when trying to reference the voltage difference to ground. From my reading it looks like I need a high-side ...
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66 views

Low Power Switching application With N-Mosfet

In my application I need to effectively switch on or off a very small load, around 0.5W to 1W. Also, I need to ensure that power loss is kept to a minimum. The voltage levels of my application will ...
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42 views

Parking Light And Signal light with same LED using MOSFETS

I have a project where I have an existing 12v parking light and I want to also have the turn signal use the same light. I've constructed a circuit using 2x NMOS and 1x PMOS. I think it will work and ...
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Biasing an Enhancement NMOS with Gate-Source Connected

I'm working on a university project wherein a full-wave rectifier is constructed using two enhancement mode NMOS transistors. I'm tasked with designing a biasing circuit for the NMOS', but I don't ...
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61 views

Additional V+ pin on ALD1106

I'm working with ALD1106 as part of a circuit I'm testing, but looking at the datasheet for the part, I'm confused by the addition of the V+ pin. It doesn't look like it's tied to anything in the pin ...
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200 views

Incorporating ALD1106 SPICE model in LTspice

I'm trying to incorporate a SPICE model of an NMOS IC, the ALD1106. I've used it before in class, but it's been so long that I've forgotten how to incorporate the files into LTspice in order to ...
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Deriving PU / PD given a sketch of a PMOS

For the PMOS given below I can derive the function f, such that f inverted in its variables corresponds to the expression of PMOS(f) and f inverted equals NMOS(f). For this specific problem I have ...
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Why would a Intel 8080 chip be destroyed if +12 V is connected before -5 V?

The Intel 8080 is a classic microprocessor released in 1974, fabricated using an enhancement-mode NMOS process, and shows various unique characteristics related to this process, such as the ...
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Find W/L and Vt of NMOS

I'm simply trying to find Vt and W/L for a given practice exam problem shown below: The solution is given as: Initially, I was trying to use the equation as shown in line 1 of the solution to ...
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110 views

Why nMOS transistors use 'Head' current source and pMOS transistors use 'Tail' current source as their load?

Here I am taking an example of common source configuration(refer figure). Generally head current source is used as load with nMOS and tail cuurent source with pMOS. Why can't be this other way around? ...
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208 views

high side switch using NMOS

I'd like to dim an ordinary 3-pin PC fan with a 3.3V-PWM at its 12V power supply pin. As I also need to measure the tachometer signal within a 3.3V logic level circuitry I'd like to switch the fan on ...
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213 views

2N7002 MOSFET gate voltage internally being pulled high, potentially dead

I am using the circuit below to switch a bi-latching relay once a wire is disconnected, i.e. to not switch as long as a voltage is present on the wire. After assembling on a PCB, on which there are ...
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55 views

Mosfet on or off

When do we say that a nMOS or pMOS is "on" or "off"? Are there any voltages across terminals we should be looking for?
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181 views

Mosfet Threshold Voltage

from MOS theory we know that, in case of a P substrate, a Gate-Bulk voltage higher than a certain threshold value creates an inversion layer, in this case made of negative charges. This is also ...
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111 views

Am I applying the KCL the right way? [closed]

Applying KCL at the node where I have drawn the currents in order to find Vin/Vs, I am not getting the correct answer which however I did obtain using the Voltage Divider. My question is, am I using ...
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Where do the electrons come from in nmos channel formation? [duplicate]

For a NMOS, when gate potential is increased from 0 to say 0.1V, the holes in substrate feel repulsion and moves away leaving negative ions behind. But what exactly happens when the gate potential ...
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93 views

Effective resistance of a NMOS

How do we calculate effective resistance of a NMOS, operating in linear region across drain and source?
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88 views

voltage divider driving PMOS with slow turn-off time

I have a voltage divider that is driving the gate of a high side PMOS switch. The voltage divider turns the PMOS on once the NMOS is turned on by a 5v logic controller. The PMOS turns on ...
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36 views

Contact on substrate of a MOSFET

Why do we want to have an ohmic contact on a substrate terminal of mosfet? What would happen if we used schottky contact instead?
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Voltage drop at gate of pmos (or nmos)

Sorry if this question has been asked before, I've tried looking through google and Stack Exchange and I can't seem to find the answer. Resistors on the gate (R3 on the picture) are usually in the K ...
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80 views

Mosfet pinchoff, why the n-channel moves towards source?

Suppose we have an NMOS transistor with \$V_{GS}\$ > \$V_T\$. When \$V_{DS}\$ is 0, the channel depth is uniform along the transistor. However, when we increase \$V_{DS}\$, the channel becomes deeper ...
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113 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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276 views

Basic questions about output impedance of a logic inverter using an NMOS

I have drawn below an NMOS logic inverter and its equivalent circuit for HIGH state: 1- Why is this gate said to have high output impedance at HIGH state? Is that because of the open switch or ...
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Sourcing the correct N-Channel MOSFET

I'm new to using MOSFETs and I need to source one for a personal project of mine. I'm using an N-Channel FET to pull down a 12v (5mA) logic/signal line from logic level (3.3v). I've used an FQP30N06L ...
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86 views

NMOS High Side switch circuit solving

I'm trying to get my head around the circuit theory behind the high side NMOS switch, here is the shematics: My question is not about whether this is a good or a bad way to make a high side switch (I ...
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how to fix output voltage of an NMOS switch with changing load characteristic?

In an NMOS low side switch the output voltage at drain depends on the operating point decided from the Id-Vds curve and load line. According to my understanding, for a low side switch with Vds ...
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235 views

What is the effect on propagation delay when we have a CMOS circuit with multiple transistors connected in series?

How does the fact that in a series connection of two or more transistors only one is connected directly to gnd (in case of nmos transistors) or vdd (in case of pmos transistors) effect the change of ...

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