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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74 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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24 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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146 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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27 views

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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36 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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28 views

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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50 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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39 views

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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50 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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84 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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80 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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149 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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136 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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50 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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129 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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107 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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68 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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72 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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56 views

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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77 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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110 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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152 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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42 views

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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Understanding PMOS's and NMOS's

The problem says solve assuming VI = 0, +2.5V, and -2.5V. I know that if VI = -2.5V the MOSFET's are in cutoff and that VDS = 0. and IDP and IDN will = 0, but would V0 also = 0? If VI = 0 the ...
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78 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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1answer
213 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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103 views

nanoPower comparator driving MOSFET not providing expected output

I built the following circuit to charge a large capacitor from a low power source before switching the load: simulate this circuit – Schematic created using CircuitLab MAX9064, MCH3484, ...
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1answer
55 views

Trying to have NMOSs in parallel while passing current through only one at a time

If I wanted to have a bias current I1 going through M1 or M2 and I want M1 to alternate between on off (M1 on/M2 off, M1 off/M2 on) would this work? I simulated this with spice and for the first ...
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1answer
701 views

ltspice: simple nmos circuit

I built up a circuit which did not work as expected. I reduced the problem to this circuit: I expect to have a current of ~2.4 A at gate voltages below 10 V, but actually the transistor does not ...
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1answer
49 views

differential amplifier and ac imput

hello im studying the differential amplifier from Sedra Smith and i have problem with the ac mode when the signal is differential (vid/2 and -vid/2) I know that in Nmos transistor the current flows ...
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109 views

NMOS current flowing equally in both directions in SPICE simulation

I am trying to characterize this nmos on Xyce simulator (and trying to change its present Vthreshold) and am first DC sweeping the gate and measuring the current through the nmos. I run into this ...
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105 views

Suitable NMOS with 3.3V gate voltage to switch 12V 500mA

I've got a circuit board with a D2PAK NMOS pad that I need to find a mosfet that will work with a raspberry pi's 3.3V GPIO. This is the current one I'm using and it isn't working well. https://www....
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89 views

High voltage switching using N-FET

This is my first time designing a High voltage switch, as come up with some interesting thing that I want to ask about. My application needs to short out a signal line to HIGH, with a 3v3 signal from ...
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1answer
171 views

Working of NMOS as a capacitor

I came across instances where NMOS was used as a capacitor in analog circuits. This is done by shorting the drain and source. The drain/source acts as one terminal of the capacitor while gate acts as ...
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86 views

Simple NMOS simulation error. High voltage drop across the nmos when trying to make a MOSFET switch

I have this simple NMOS configuration in ltSpice. I would imagine that when V2 (Vg) goes high, Vds would go close to zero. But this simulation suggests that there is a very high voltage drop across ...
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1answer
156 views

Why does the PWM signals amplitude drop once connected to low-side n-mosfet switch?

I am applying a 3.3 V pwm signal to a circuit similar to the following (Credit: Olin Lathrop): I am using an IRLR024N N-MOSFET, which switches if i connect the gate to the 3V3 pin of my ...
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366 views

TSMC model for lt spice simulation [closed]

From where to download the tsmc model file for nmos(slow,fast,typical) and pmos (slow,fast,typical)?
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Simulating process variations

How to simulate Drain current vs Drain source voltage characteristics of a NMOS with respect to process variations in LT Spice?
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303 views

Difference between body, bulk and substrate?

I have a pretty fundamental question related MOSFET devices. I am confused about whether the terms body, bulk and substrate are all just names for the same thing or are there actually some differences ...

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