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)

learn more… | top users | synonyms

0
votes
1answer
13 views

DC-to-DC voltage booster mosfet heat problem

I'm tying to understand boost and buck converter designs. Recently I made a prototype of a simple boost converter, used this as a reference. Used parts are as follows: Transistor - IRF3205 Diode - ...
1
vote
1answer
43 views

Mosfet won't turn fully on

I have a IPB011N04LG N channel MOSFET configured as a switch in the following circuit: It works, but doesn't turn fully on. If \$V_{\text{BAT}}\$ is \$23\$V I get \$11\$V on the load side If ...
3
votes
2answers
30 views

Current source as load in a differential amplifier

In Design of Analog CMOS integrated circuits by Razavi I found the following differential pair design. It uses a MOS as load and it acts as a current source. My question is how should you bias the ...
0
votes
0answers
34 views

Stepper Motor H Bridge High Side N-Mos Burn Problem

Last year, i designed a stepper motor driver card with DRV8711 and CSD17506. I am driving my stepper motor with Vm=24 Volts and motor current Im= 2.14A. Texas Instruments gate driver drv8711 is ...
0
votes
0answers
26 views

Control Output Power using PWM from Arduino

I am trying to make a simple control loop to power up a lamp and with that control the temperature, for that I am using an Arduino as microcontroller. The lamp I am using is a DC 12V 20W, so we ...
0
votes
0answers
31 views

Dc Motor drive setup

I would like to ask why in this setup the dc motor is parallel to the fet and what is the reason for the diode. Thank you!
0
votes
0answers
53 views

Amplifying Signals to a Certain Voltage

Say I have some high frequency low signals and I want to amplify them to peak at +/-9V or something. Yet the chosen Fully Differential Opamp is only powered at 5V. So even if the Opamp were to go to ...
0
votes
1answer
41 views

Is it permissible to use fractional aspect ratio W/L for MOSFETs?

I am designing a 2-stage op-amp (Miller compensated). For compensation, I am using a nulling resistance R in series with the compensation capacitance C, with the resistance implemented using a ...
0
votes
0answers
26 views

Controlling a three-wire valve via µC and transistor-based SPDT

I am building a garden watering automation thing. An MSP430 controls a 12V three-wire motorized ball valve (CWX15Q CR-02). One wire is GND, one is OPEN and one is CLOSE. Now I need a circuit to ...
2
votes
2answers
29 views

Switching polarity of rectified AC power with a microcontroller

I am trying to create a circuit that will allow me to control the polarity of the current flowing through a coil in order to attract or repel a magnet. I would like to use two MOSFETs in series since ...
0
votes
2answers
35 views

Voltage shift 5V to 3.3V for PIC16LF145x 3.3V I/O input, several approaches

For USB device detection I need a way to shift that VBUS 5V to 3.3V in order being able to connect it as I/O input pin. The input pin should be high as long as VBUS = 5V, and low as soon as VBUS = 0V. ...
-1
votes
0answers
37 views

Vape Pen Circuit, 3 main components. Wiring/component help?

I'm looking to control a vapor pen with a variable voltage (adjustable PWM that dictates a MOSFET), followed by a SPST toggle (safety), followed by a momentary that dictates another MOSFET. The goal ...
0
votes
1answer
38 views

MOSFET representation

In my book I often see the N-type semiconductor both drain and source being shown as n+ whereas the p-type semiconductor or the substrate is shown/represented as p only. Why is N-type semiconductors ...
0
votes
0answers
18 views

Triggering Problem in 100W LED driver

Why a triggering problem, 100 Watt Driver(volts @ 3ampers), instantly it switches On, but once it is off again it wont switch on.Why does this happens in a led driver. Is this due to capacitors ...
0
votes
0answers
39 views

MOSFET functionality

Why is that the depletion region beside the DRAIN in MOSFET increases in area after pinch-off ? {Keeping the voltage VDS increasing even after pinch-off increases the area of depletion region below ...
0
votes
1answer
90 views

Help on transistors or MOSFET in 8x8x8 LED cube

I am on a project to build a 8x8x8 LED cube having common cathodes in each layer. I have built the cube and now I have to build the main circuit. I am using my Arduino Mega 2560 to control it. I ...
-1
votes
2answers
93 views

P-type MOSFET is not turning off

I am designing a buck converter as class assignment as shown in figure. I have calculated all the value of inductor and capacitor. I am applying PWM to the input of MAX627 MOSFET driver through ...
1
vote
2answers
44 views

Designing a MOSFET current mirror circuit

This is the design problem: This is a brief of my design for W and L of the transistors and R: I've connected the upper voltage source to ground and made the lower one equal to 0.4 V to make ...
0
votes
1answer
25 views

Comparator model suggestion for overvoltage protection circuit

It's a pretty simple circuit. I'm measuring a voltage with an ADC, which has a max input of 5V. The signal I'm measuring goes to the drain of a F12N10L MOSFET. The MOSFET's source is connected to ...
0
votes
0answers
28 views

how to solve mosfet size match error in tanner 14.1 for 0.18um process

I have refer your answer for spice simulation. but it is not going with 14.1 version. please help me with respect to 14.1 version.
0
votes
1answer
72 views

Designing E-Cig, need some help with the schematic and components [closed]

So I'm in the process of gathering all the parts needed for an e-cig (vaporizer). Will be using a Lithium, 3.7V nominal battery, heating up a coil that will be somewhere between 1 ohm and 2 ohms (this ...
0
votes
2answers
64 views

H-bridge mosfets exploding

Something odd is happening in a h-bridge design I've made. Schematic: The part numbers in the picture are wrong, sorry. The n-channel mosfets (the bottom 3) are all 2N7002Ps, and the P-channel ...
0
votes
2answers
42 views

MOSFET as a switch. Why does the voltage depend on the gate?

Let's say I have an NMOS, the gate is connected to 5 volts, Vth is 0.7 volts and I want to pass a voltage of 7 using the NMOS as a switch. Can you tell me what will be the voltage at the source? Will ...
0
votes
2answers
69 views

Multi-stage amplifier coupling

For my final project in my electronics course this semester, I need to design an amplifier with a specific set of parameters. Specifically, it needs to have a gain of 100, a voltage swing of at least ...
0
votes
1answer
33 views

How to power a 6-12v Piezo siren from an Arduino?

We are trying to power a Piezo siren, which requires 6-12v, from an Arduino, which only outputs up to 5v. We are planning on using an external 9v battery to power the Piezo siren, although we do not ...
3
votes
1answer
182 views

Analysis about H bridge to drive DC Motor

the picture below shows my design about driving DC motor with H bridge. There is one problem, for example, I turn on the U1B and U1A(use PWM to turn on U1B and the U1A is always turn on when I make ...
0
votes
1answer
67 views

Buck converter not working

I designed a buck converter on breadboard as shown in the picture. I am applying PWM from my microcontroller. I am not sure why this circuit is not working, I have spent so much time on it. Is there ...
2
votes
1answer
57 views

Hybrid \$\pi\$ Model vs. T-Model Input Resistance (MOSFET)

If the hybrid-\$\pi\$ model and T-Model are equivalent models, why does the hybrid-\$\pi\$ model have an infinite input impedance and the T model has an input impedance of \$1/g_m\$ assuming ...
0
votes
1answer
49 views

Looking for N-Channel MOSFET with igss<10nA [closed]

I'm looking for a surface mount mosfet with a gate leakage in the pA or very low nA range, so I can drive the gate from a very high impedance source. Since most people don't care that much about igss ...
0
votes
1answer
66 views

MOSFET switch replacement not working

I'm using a PNP MOSFET to replace a physical button. When I ground the lead I've attached to bypass the switch, the action I need activates (a notification light comes on - it's the activator button ...
0
votes
1answer
77 views

using a MOSFET to switch a voltage lower than the gate

I'm using a p-channel mosfet to switch a 3.5V load, using a gate voltage that's ~5V. The gate goes from 5V to 0V, but the mosfet doesn't start conducting. Did I just fry the mosfet by having the gate ...
0
votes
1answer
70 views

DC motor - Transistor / Mosfet - Design

The one on the left seems to work neatly. But the right ones' motor goes way slower. Though, I did find the right one on the internet (and internet is always true). My thoughts: The amount of ...
2
votes
2answers
72 views

Is this the behavior of a broken mosfet?

I designed this circuit to switch on/off 8 solenoid valves for a programmable dancing fountain that I am building. The GPIO is coming from a Raspberry Pi. VCC is coming from a 12V deep cycle car ...
0
votes
0answers
28 views

Voltage-mode or Current-mode PWM controller?

I am trying to decide between a voltage-mode and current-mode PWM generator to connect to a gate driver IC to drive my power MOSFET. The PWM will be generated based on a current input to the ...
0
votes
2answers
42 views

Current-controlled PWM Generator with variable duty cycle?

I need to implement a variable duty cycle PWM generator with constant frequency (100kHz) to help drive a MOSFET. Is there such a thing out there in the market or is it something I need to build with ...
1
vote
2answers
144 views

Selecting a transistor for high-side switching at 5V with a 2A load current

I'm doing a high side switching of 5V 2A load and will be ON or OFF for long time(1-10 hours). Now I'm confused about which transistors should I use ? or MOSFETs ? Do I need heatsink ? I really ...
0
votes
1answer
49 views

Using p-Channel MOSFET as a Switch to turn load on / off via BeagleBone Black GPIO

Is this the correct way of using a pMOSFET as a High Side Switch? I need a Load Device to be turned on/off (Vin Pin). The Load Device requires 5v 700mA power to run. My logic is, when the ...
0
votes
2answers
62 views

Short-circuit primary side of a transformer to collect all the spikes at the secondary

Abruptly detaching a power source from a coil produces a back-emf: this is a well known fact. What I would like to achieve, in my experimentation, is to convey ALL the collapsing magnetic field to ...
1
vote
2answers
67 views

Mosfets cooled with Heatsink and fan?

For my circuit, I have mounted heatsinks to my mosfets to dissipate heat. I have below a crude drawing of how the heatsink/mosfet is placed on the PCB I was thinking to integrate a LM35 to measure ...
0
votes
2answers
48 views

What is the dependance of voltages in a MOSFET on its Performance?

The Wikipedia page says that (in context of scaling) To maintain performance, the threshold voltage (Vth) of the MOSFET has to be reduced as well. And also, this paper says, For high ...
1
vote
1answer
67 views

How to find the Q point of the NMOS trsistor 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 ...
0
votes
0answers
38 views

MOSFET T-model question

In the attached diagram, I do not understand why the current source I becomes an open circuit and the voltage source Vdd becomes grounded. If someone can clear up this simple question for me, it'd ...
0
votes
2answers
59 views

Diode parallel to resistor on H-Bridge MOSFETs gates

I was looking at a TC4467's gate driver datasheet and there is one thing there that I haven't seen before when reading about H-Bridges. On the schematic of example H-Bridge motor control there is a ...
0
votes
3answers
75 views

Dual Mosfet Not Gate Getting Very Hot, Critique Circuit

I have put together this circuit from parts I had lying around, It is to invert a normally closed momentary switch to behave like a normally open. The switch is for a car and toggles a tail light. ...
0
votes
0answers
41 views

What are the two big transistors on a ESC

Looking at an commercial electronic speed controler for a brushless motor, there is two big transistors on one side. For controling a motor, you have to switch the current on three wire, so you need ...
0
votes
0answers
36 views

P-Channel FET Switching Time

I have a question about the circuit shown below. Specifically, I am looking to calculate the time that it takes to fully enhance the PFET and activate 3V3_SW1 after the control signal transitions ...
0
votes
5answers
74 views

Reducing the voltage drop on a simple comparator driving a MOSFET to avoid LiIon overdischarge

I would like to use a LiIon cell recovered from an old laptop to power my bike light (a bulb one, 2.4W 6V). I thought about using an opamp controlling a MOSFET to avoid overdischarge (MOSFET ON for ...
0
votes
0answers
39 views

Field Excitation of synchronous motor with MOSFET+ Arduino ( MOSFET accessories design)

Abstract: I am trying to make an automated system, that monitors the system's voltage, current, all powers and power factors. This data is wireless sent to a substation(prototype model, imagine=master ...
0
votes
0answers
10 views

How to add different models for different transistor in tanner t-spice?

I am working in tanner 15 at 180nm technology. I have a circuit in which transistor have different threshold voltages so is need to define model file for each transistor how to do that .... I tried ...
1
vote
1answer
47 views

What could be the target applications for these BJTs?

NXP recently introduced a new family of BJTs with switching capabilities of up too 100V, 10A , see "The toughest bipolar transistor - 100 V in LFPAK/Power-SO8". I cannot think of a switching ...