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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How to size CMOS transistors

I am new to CMOS technology and I am trying to learn about CMOS logic gates. I have a problem with transistors sizing. As far as I could understand the main idea is to obtain equal rise and fall ...
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52 views

How to do DC Analysis for a Common Source Biasing Circuit using NMOS

I am having a lot of trouble with this specific problem. I want to find Vg, Vd, Vs, and Id for this specific common source biasing circuit that has an NMOS. I have these values given: Vdd = 9V, k/2 = ...
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29 views

Input and Output Load Lines

In parts b and c, what is the input and output load lines? Thanks
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115 views

N-MOSFET switching an H-bridge: problems with PWM

In this circuit an Arduino digital pin drives the Gate of a N-MOSFET. When the pin is HIGH, current can flow from the H-Bridge GND to board GND. When it's LOW, current can't flow. What I need is to ...
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47 views

N-mos will not go into cutoff

Am I missing something? It is my understanding that if Vgs is less than Vtn than the n-mos should be in cutoff with no current flowing from the source. I have drain hooked up to 12v in series with a ...
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68 views

NMOS/PMOS logic vs. CMOS logic

With PMOS and NMOS, one can deduce that it is off, if Vgs < Vt (NMOS) || Vsg < Vt (PMOS) id = 0. Now my question rests on the dependency of these conditions. I know proving condition 1 ...
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85 views

PMOS and NMOS in cut-off

I am confused regarding the voltages of NMOS and PMOS. For a NMOS, let us say it is in cut-off, thus making Id = 0. Then does that mean Vds = 0? I was initially under the assumption that Vds can be ...
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55 views

Can an NMOS act as an NPN BJT if Vds is high enough?

The physical layout of a MOSFET is very similar to BJT transistor, if we ignore the gate. Normally a FET requires a gate voltage to turn on and allow current flow from Source to Drain or vice vera. ...
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1answer
81 views

Threshold voltage of a pseudo nmos inverter

How can I find the Vm of a pseudo nmos inverter? Since I dont know the Vds of neither of my transistors I cant determine in which region they are. The circuit and some parameters are in that link. ...
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92 views

Current source load mosfet

Guys I have a silly doubt. above is a standard circuit. I wish to ask how can a small signal current exist through the transistor shown above? The current source ( which is dc) will always force the ...
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57 views

Biasing using constant current source

guys i was going through this diagram in my book when these lines came along(i am a student): Here RG(usually in M-ohm range) establishes a dc ground at the gate and presents a large resistance to ...
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71 views

Voltages to keep my circuit running at 200mA with NMOSFETS

Im trying to build a circuit to send information using IR led, using pulse signals my leds (TSAL6400) operates at 1.35V, and their maximum pulse current is rated 200mA After struggling a bit with ...
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147 views

3-pin MOSFET: P or N type?

This may be a silly one but I couldn't seem to find an explicit answer: with a 3-pin MOSFET, how do I determine whether it's an NMOS or PMOS? I'm making some assumptions here: I've already found ...
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291 views

Need gate driver for MOSFET (IRF540) and microcontroller

I'm trying to use a STM32F100RBT6B microcontroller to turn on a n-channel MOSFET (IRF540) to switch on a voltage of 24V to an electrical magnet. I understand I would need a gate driver between the ...
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49 views

Basic Nmos amplifier working

I am trying to understand this circuit here. I do not understand clearly how this works. I know that the PMOS is a current source but what impact does the resistor Rb have on this ? Could anyone ...
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56 views

Trying to simulate the linear region of a MOSFET

I wanted to simulate the linear region, so I tried this: simulate this circuit – Schematic created using CircuitLab I expected the triangle wave to be curved, but it didn't have those ...
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43 views

Can a NMOS transistor be used as a Current Controlled Voltage Source?

Assuming an NMOS transistor is in saturation. Can you apply a current \$I_{DS}\$, resulting in an output gate-source voltage (\$V_{GS}\$)?
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129 views

NMOS - Why is a resistor necessary?

I understand how the logic levels of an NMOS work with a pull-up resistor. 1. What would happen though if there was no resistor attached? (What would the logic levels look like and why?) 2. What ...
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77 views

Depletion Mosfet working as enhancement NMOS

The depletion mosfet can also operate in enhancement mode when the gate voltage is positive (say for depletion type NMOS). My question is : Will the Shockley equation be still valid in the ...
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1answer
206 views

Bias common source diode connected load

To amplify small signal we need to bias M1 and M2 in saturation mode. Obviously, M2 is always in saturation because Vgd = 0. However, how should I bias M1 in saturation?
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59 views

Biasing an NMOS to get rid of \$V_{th}\$

So here's a common way of cancelling out the \$V_{th}\$ in an NMOS. Am I better of use a good quality zener (in series with a resistor) or stick with voltage divider R1 and R2 below. Assuming we can ...
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127 views

MOSFET shorted after I connect them in parallel, what's wrong?

One of my MOSFET source-drain shorted after I connect them in parallel? So I was making an ARC speaker yesterday, and I used one MOSFET ( irf540), and it got really hot, but it did not blow up, so I ...
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179 views

SOT-23 NMOS transistor power dissipation

I am working on a design of a control system that controls a few small solenoids, each drawing about 200 mA of current and operating at 15-18 V. These solenoids are activated by NMOS transistors. Due ...
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100 views

Simple NMOS transistor circuit output impedance

I am having trouble figuring out the best way to determine the output impedance of this simple NMOS transistor circuit: Both transistors are equal, and the body effect is ignored. What method ...
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344 views

CMOS: Why is an nMOS transistor a bad conductor of high logic, but a good conductor of low?

I can't find an answer that addresses this and makes sense to me. I know that V_t is subtracted from the 'output', but I don't understand why.
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90 views

Gate voltage and drain current relation

I am new to electronics and have the following doubt. Say Vgs= 3V to a NMOS produces Id= 3A. Now if we place a 3A current source at the drain,will it cause a 3V at the gate, when the gate is open ...
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1answer
85 views

High Drain Current MOSFET vs Low Drain Current MOSFET for Synchronous Buck Converter

For a battery charging application, i have to build a synchronous buck converter (i/p voltage = 12V , o/p Voltage = 4.5V) which would be driven by a PWM signal from the micro-controller. This Buck ...
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1answer
104 views

Tristate logic equivalent in NMOS logic

Suppose I have 3 signals generated by NMOS logic. Each of those signals has an associated enable pin that when driven high will result in the value of the signal appearing on the output (I should note ...
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1answer
98 views

Pull up resistor in NMOS logic value

For my senior high school project I decided to build a basic CPU from discrete components. I plan on using a 5V logic level and the current design calls for around 2000-3000 N-channel MOSFET ...
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1answer
49 views

Capacitor problem using an NMOS inverter with depletion load

When Vin is low the enhancement type NMOS is off. That means the drain current of both transistor is zero, isn't it? If it is, then how will the parasitic capacitor charge? I'm not understanding! ...
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2answers
492 views

Why is CMOS fall time faster than rise time?

I've just started a computer architecture class, and the slides from a lecture says that the reason why fall time is faster than rise time is that the NMOS electrons have more mobility than PMOS which ...
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471 views

NMOS and PMOS current sources

I'm really confused with the representation of PMOS device shown in the figure. Since conventional current direction in PMOS is from source to drain, shouldn't the current source be pointing ...
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3answers
297 views

Single MOSFET Amplifiers

Why is it that when I see single MOSFET amplifiers or even complementary ones (one NMOS and PMOS), they would use what in single BJT amplifiers would be called "Common Emitter Amplifier". The output ...
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1answer
49 views

Enhancement type nmos threshold voltage

in an enhancement type nmos when a channel is created then a depletion layer should be created under the n-channel which means electrons get a potential barrier to overcome.now is this potential ...
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78 views

Finding 2nd Vds value in a NMOS circuit

I think for the first part of this problem I solved for Ra = 13kohm and Rb = 7kohm, but I'm not able to understand or see how to get the voltage at the point V1. Any idea on how to go about finding ...
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49 views

Depletion NMOS that's saturated at 0V

May seem like a weird request for a part, but are there any Depletion NMOS out there that is already saturated when you apply 0V to gate or if the gate is not connected?
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2answers
256 views

Help with MOSFET buck converter

I've started learning about Buck Converters, and I made a miniature one on an Arduino prototype shield. But when I turn the thing on, the voltage is stuck at 5v (the voltage input). I tried ...
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1answer
70 views

what would the drain voltage be if NMOS source voltage is not ground?

Hi I'm a beginner trying to learn CMOS cuicuit. Let's say we have two NMOS connected as shown. Given: A, B, C are connected to Vdd = 5V; VtM1 = 0.6V is the threshold voltage of M1; VtM2 = 0.5V ...
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1answer
57 views

NMOS saturation mode: why is there no channel?

I have a question about the saturation mode. The cross-section of an NMOS transistor in saturation mode is usually drawn like this: But it seems to me that there can be no current from source to ...
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1answer
37 views

NMOS amplifier simple question?

While studying the NMOS amplifiers in my book I came across operations with differential output voltages and this circuit specifically.I want to understand what are the drain voltages and what is the ...
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1answer
418 views

How to find the Q point of the NMOS transistor in Voltage-Divider Biasing Circuit?

The following is the circuit needed to be analyzed to find the Q point(\$V_{GS_Q}, V_{DS_Q}, I_{D_Q}\$). \$V_{TN}=1\text{V}\$ \$K_n=0.5\text{mAV}^{-2}\$ simulate this circuit – Schematic ...
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1answer
42 views

Help with NMOS Gate question

In this picture, when v1 and v2 are 0, M1,M2 are on and M3,M4 are off. V_T(threshold) = 1.7V, V_DD = 5V. Why is it that M1 and M2 are ON under these conditions? I thought when there is no power ...
2
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2answers
251 views

DC analysis of common source MOSFET circuits to find gate voltage using different power supplies

simulate this circuit – Schematic created using CircuitLab strong text I am solving problems on DC analysis of MOSFET circuits. We are supposed to find various parameters like Id(Drain ...
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1answer
54 views

NMOS Channel Type

I've seen some conflicting information about the inversion channel for an NMOS device. Is NMOS n-channel or p-channel? And is the substrate n or p? I know PMOS is just the opposite for both and the ...
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2answers
1k views

Create a CMOS circuit from a logic function [duplicate]

I have to create a CMOS circuit from the logic function: F= ~A + B (notA or B). I made the truth table but I'm stuck here trying to make the CMOS circuit. Any ideas anyone? Thanks! I know it's the ...
3
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1answer
197 views

CMOS technology, use a NMOS or PMOS as series switch?

A general question regarding switches in CMOS. Have a look at the schematic below (symplified current mirror) There is a input reference current, on/off switch, a PMOS mirror and the resulting ...
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1answer
79 views

Stable solution

To my understanding a stable solution for a transistors is when the voltage will not fluctuate due to to a change in Vin or something like that. My question I guess would be, where would I start ...
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1answer
87 views

Why feedback is activating at more than 4V?

In this circuit: I don't get why the current start flowing from more than 4V. I thought was due to threshold, but the same happens with an NPN as M2 or using an BS170. With this last one, ...
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2answers
92 views

Trying to find steady state

I'm taking my first course in electronic circuits and I'm a little lost when it comes to combining NMOS transistors with capacitors. In particular I am having trouble with finding the steady state for ...
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1answer
171 views

Source potential for MOSFET with grounded substrate

Considering the configuration below, the source's potential should be invariant with respect to Vg (as long as Vg>Vt). So Vs is equal to Vdd. But if the substrate is connected to the source, as ...