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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617 views

What is the significance of FO4 inverters in CMOS static circuits?

With regards to the image above, I wanted to know what is the importance of Fan Out of 4 (FO4) for optimum design and what improvements does it incur over designs that are either higher or lower than ...
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172 views

High side driver schematic

I'm working on an android controlled input/output/gauges manager for cars based on a pic24 micro controller. I'm really not an electronics expert so I had someone working on the schematics but he has ...
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83 views

Need a switching circuit that is closed when Vgs is negative and open when Vgs positive, any ideas please?

I need a circuit that will be closed when Vgs is negative and open when Vgs positive. Basically the inverse of Enhancement mode MOSFETs or JFETs. I appreciate your help with this. Thank you!
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4answers
753 views

BJT or Mosfet as Cascode

I was going through this lecture pdf. If I want to have maximum output resistance which cascode configuration I should use. BJT cascode or Mosfet cascode?
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84 views

Powering off a switching regulator causes MOSFET to briefly blip on. Arduino

I have stumbled upon a weird issue in my circuit below, that only happens when the DPDT slide switch, S1, goes from an upwards position(On) to the downwards ...
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186 views

Battery backup circuit

I want a battery back up for a monitoring system. Power supply is 4.8V-6V. Battery is 4.8V-6.4V (with 100uA leakage it goes 4.8V after one year). I designed this circuit but on simulation it ...
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1answer
159 views

Difference between mosfet

I'm working on a 3 Phase brushless sensorless driver ( Allegro A4960 ) I need to drive different motor in term of power. The voltage is 24V but the current per phase varies from 1A to 6A. So I'm ...
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1answer
35 views

Reverse Polarity Protection for DAQ box

Firstly, I am a ME seeking advice from EE's. I have a Quadvolt voltage data acquisition box from Omega (P/N: OM-CP-QUADVOLT-30V) http://www.omega.com/pptst/OM-CP-QUADVOLT.html, that I intend on using ...
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34 views

logic mosfet instead relay to in central phone

I want to have a inter communication between two phone.I need to know how can I do it without relay in fact I want to do it with mosfet.Is it work? If answer is yes,can I use mosfet in both of line (...
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2answers
293 views

what is the ideal number of contacts to be placed in NMOS and PMOS when drawing layout in Cadence virtuoso

I am trying to draw a layout for inverter and i am not sure about how many contacts to be placed in the diffussion region of NMOS and PMOS and what is the reason behind selecting that particular ...
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45 views

Concerning rds in MOSFET

Why is \$r_{o1}\$ connected to the ground in the second diagram which is the small signal equivalent (formal solution, hence most likely correct)?:
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1answer
156 views

PMOS reverse polarized - 12v light

I've this circuit: simulate this circuit – Schematic created using CircuitLab I have a doubt, when I press the SW1 the LAMP1 turns on, when I press the SW2 the light turns on but the P channel ...
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249 views

Microelectronic Circuits Sedra Smith (drawing tool)

I'm looking for the tool used in the reference "Microelectronic Circuits" (or similar) to draw the circuits. e.g. For the n-channel enhancement-type (circuit symbol c). Any help?
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237 views

Cgs,Cgd capacitor in Mosfet/ problem with measurement unit

I am a little confused with this problem. I would like to ask if I have a Mosfet(in saturation)and I have find that Cgs=16fF and Coverlap = 0.5fF/um(this is given in the description of the exercise), ...
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885 views

Overdrive voltage and Early effect in MOSFET

Can anyone explain to me if there is the Early effect in MOS transistor then the Early effect affects the expression for VOV which is \$VOV=\sqrt{\frac{2ID}{kn'(W/L)}}\$?
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79 views

Is length in FinFET changeable?

I have a simple question. I need to make the PFET or PMOS FinFET weaker than minimum size when nfin=1. So Can I change its length from default to l=2n in the netlist for simulation? It worked but I ...
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587 views

Gain of a differential amplifier with active load

Can anyone help me to find which is the type for the gain of this differential amplifier for common mode input.I had find that is Acm = 1/(gm3*2*ro5).Can anyone help me if this result is correct and ...
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1answer
66 views

Help me correct this circuit with N mosfet

I am trying to build a protection for my circuit in case someone attached batteries or any power supply in reverse even if the other supply is normally attached. As you can see I have 2 power ...
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32 views

What do i have to change to use it with 24V 10A motor [duplicate]

I have built this scheme But this works only with 12V because of Vgs=20V. My question is: what do i need to change in this scheme to make suitable for 24V?
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1answer
77 views

Need help selecting a mosfet to vary switching regulator output [closed]

I am looking for a mosfet to dynamically vary the output of a TPS61236 switching regulator: 5V and 5.5V (need only 2 set voltages). A simple solution according to this article would be to add a mosfet ...
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78 views

Implementing non-linear time delay

I have a feedback system including an OP-amp in comparator mode and a transistor, in present time it acts like a regulator, constantly limiting the current through the transistor to a certain value. ...
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2answers
581 views

Selecting low power mosfet for battery monitor

I'm trying to implement og test the results discussed in the linked JeeLab post in a low power battery powered device. http://jeelabs.org/2013/05/18/zero-power-measurement-part-2/#comments The post ...
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1answer
157 views

SI8751 isolated mosfet driver and msofet NVD5C668NL

I need help for my very first application with power mosfet The goal is "simple..": create a SSR for switching a generic DC load with variable power supply from 5V to 48V and max 25A. Isolation isn't ...
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494 views

Polarization of 3 MOSFET

How can I calculate the polarization parameters for each MOSFET transistor? There is an internal resistance in the input signal of 100k. RS1 = RS2 = 423 \$\Omega\$ and Vdd = 17 V. I got two values ...
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300 views

MOSFET Current Source

Implement a current source, with cascode topology, using Diodes Inc's 2N7002K MOSFET, satisfying the following requirements: Use a voltage source of 5.5 Volts \$ i_{out} = 6 ~ \mu A\$ \$ V_{out_{min}}...
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1answer
105 views

Mosfet Amplifier Problem

I'm currently working on a problem that wants me to obtain a gain of 500 using a mix of CG CS CD or cascode amplifiers or just a single topology. The Vout will be powering a resistive load of 50 ohms. ...
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1answer
377 views

Low-frequency response of a CS amplifier

I would like to ask for the sentece below in the the red box if fp2=400Hz, fp2=100Hz and fp1=60Hz then I can assume that fL=fp2=400Hz? And the other case if fp2=300Hz, fp2=100Hz and fp1=60Hz then fL=...
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1answer
40 views

Biasing using Current Source

Note: (W/L)ratio of M5 = 3 * (W/L)ratio of M7 I would like to ask if there is a preferable method for accurate current mirroring between the two schematics below. To make it clear what I would like ...
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2answers
125 views

MOSFETs leaks current between two water sensors

Goal: I've got a set of EC and pH water sensors that need to sit in the same batch of water / capture values real-time for a Arduino project. However my sensors cancel each other out when both are ...
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254 views

In-rush current limit MOSFET, resistor

I'm using DC/DC converter LTC3112 to supply GSM module. Battery source is about 12V and DC/DC output is 3.7V. Microcontroller logic is 3.3V powered from other DC/DC converter. The application is ...
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1answer
348 views

Avoid neopixel power on USB

I am designing a lamp based on neopixel leds and arduino. I'm designing the badge on Eagle and I've noticed a problem. I have noticed that with the consumption of the LEDs (5A) when the user tries to ...
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2answers
1k views

KVL and KCL in MOSFET small-signal model, how?

I want to find the gain in this MOSFET small-signal model. KVL in loop 1: \$+V_{in}-V_{gs}-g_mV_{gs}R_s=0 \iff V_{in}=V_{gs}(1+g_mR_s)\$ KVL in loop 2: \$+V_{out}-g_mV_{gs}R_s=0 \iff V_{out}=g_mV_{...
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1answer
233 views

How to choose mosfet for DC AC flyback [closed]

I am working on dc ac flyback We have got 35 Volts for the Panel and the grid 120 volts (RMS) 170 V, 60 HZ I am trying to choose the right mosfet, I need for M1 S1 S2 ( after the diode D1 and d2). ...
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1answer
73 views

Sanity check on an open drain buffer (pull-up to 3.3V but 14V on gate?)

I want to make a simple open-drain buffer using the 2N7000 MOSFET. The input signal on the gate (Vgs) will be 14V and the voltage it is switching is 3.3V (Vds). Usually MOSFETs are used to switch ...
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47 views

Comparing Power Mosfets - value of Rg

I want to build an inverter and currently I am in the processing of choosing the right MOSFET. To achieve this I use simulations to compare the total power dissipated on the MOSFETs, to see which one ...
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1answer
63 views

biasing of an NMOS

Suppose I have applied a constant current source(of value I) at the source of an NMOS ,the gate is grounded and the drain is connected to a voltage source with resistance R between them. Equation of ...
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748 views

How to get 6V DC motor running using PWM through STM board

First image is edit of image 2. Use this circuit to build unidirectional motor control using PWM. Ignore 3v pin, MOSFET can be any mosfet having small threshold gate-source voltage eg, 30N06, ...
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141 views

Turning on/off MOSFET using 4000 series CMOS

I intend to use 4000 series CMOS running at 12V to turn on some power MOSFETs (SUM55P06 and IRF2903) handling 8A at 12V. However, the arrangement of logic gates I need to simplify the driving s/w ...
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66 views

Smoothing potential 30kHz noise in battery “switcher”?

I've created a circuit that switches individual items of avionics (for my glider) between two 12V batteries. The idea is that I can switch items between battery A or B depending on how the batteries (...
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94 views

Voltage induction on MOFET gate?

I am trying to design an amplifier that will amplify input audio signal by about 2x when input peak voltage is below 500mV. If above it should act as a unity gain amplifier. I've designed below ...
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402 views

Power MOSFET versus regular MOSFET Silicon Layers

I am having some difficulties differentiating between a power MOSFET process and a regular MOSFET process. Here is a regular MOSFET silicon layer stackup: The n+ doped region for the source and ...
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354 views

how to measure mosfet impedance in LTspice?

I am trying to design a 13.56MHz 20W class E amplifier based on a TI app note this. On page 5, it say "FET(IRF510)’s gate impedance is 14-j26", which I should match impedance to my driver output. ...
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1answer
541 views

Design CMOS comparator

I made the circuit. like this paper, But It's not working. When you insert the AC input, a square waveform should appear. I can not interpret the circuit well. If you know anything, please answer ...
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1answer
124 views

n-EMOSFET circuit analysis

This circuit is n-EMOSFET circuit, VTH=3V, K=1mA/V2, find VGS, ID and VD. Vo = 15-3300ID ID = (15 -Vo)/3300 VD = 3300ID Since IG=0, VGS=VDS=Vo ID = (15 -Vo)/3300 = 1mA/V2 (VGS- VTH)/2 ID = (15 -...
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57 views

Controlling NMOS

Can I control a NMOS (don't look the reference in the schematic) to shutdown a LDO with a voltage detector like so ? Or is there missing something? simulate this circuit – Schematic created ...
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1answer
70 views

what sort of switch can I use? [closed]

Noob here, with a basic question. I am looking for a switch to close a circuit not straight to ground. P channel MOSFET seems fitting, but I would like one where to keep the switch open, it does not ...
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1answer
378 views

Lipo battery protection circuit. Is this a good approach?

I want to build a circuit for a quadcopter where MOSFETs are connected to the primary and secondary battery. When the voltage falls below certain value in the primary battery the voltage monitor ...
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0answers
157 views

Problem with dual channel back-to-back mosfet AC dimmer

I'm having a problem with a two channel mosfet dimmer that I'm constructing. When I had only one channel (T1_signal and Load_1_Live) populated on the PCB in the schematic below the dimmer works fine. ...
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139 views

N MOSFET bi-directional level shifter draining Vcc possible?

I'm not a specialist in analogue electronics, so my question can be a very simple for someone to answer. I have a bi-directional level shifter built with N-channel MOSFET as on picture below. It ...
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1answer
112 views

Channel shape of NMOS in saturation

According to the Sedra/Smith Microelectronic Circuits textbook, 6/7 eds., increasing \$v_{DS}\$ beyond \$v_{OV}\$ has no effect on the channel shape and charge. Why is that? It seems as if (...

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