Mosfet Problem |
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1000 Threads found on edaboard.com: Mosfet Problem
I would use an optocoupler like the hcpl2201 with a bipolar push-pull stage after it to deliver enough current to turn the mosfet on and off quickly enough.
Your problem there is a very slow turn off time.
Hobby Circuits and Small Projects Problems :: 01.02.2009 23:08 :: R00KIE :: Replies: 38 :: Views: 10349
I'm using components from the same manufacturer. If you say got parasitics or losses problem, why it didn't affect S22?
Sorry, I'm still no idea what happening here...
I agree, if you have a short or open at the input, the gain (or S21) will be low.
But S11 could be different from the simulation when other S-parameters are relativ
RF, Microwave, Antennas and Optics :: 24.10.2009 10:30 :: stevie-g :: Replies: 7 :: Views: 917
Hello to all.
I am trying to design a VCO in 90nm TSMC. The problem is that the current mirror i am designing has large mismatch between the Iref and the Iout. I am using rf nmos transistors to design it. The model i have available has maximum length in nmos 240nm. Can i use a dc mosfet to design the curent mirror?
Thnx
Analog IC Design and Layout :: 26.03.2010 15:14 :: nmakris :: Replies: 4 :: Views: 904
Is your question related to the leakage current of the mosfets?
A mosfet can't turn completely off , there is a current of a few uA passing through the mosfet even when it is off, the parameter is described in the datasheet.
Alex
Electronic Elementary Questions :: 13.09.2011 18:06 :: alexan_e :: Replies: 20 :: Views: 467
Hi
I have been researching and reading everything i can about mosfets and H-Bridges and have come up with the attached schematic.
can someone please tell me where i have gone wrong and why i keep destroying my mosfets.
I am wanting to run a single small motor in both directions with variable speed.
I have a switch mode 9v power source com
Microcontrollers :: 14.07.2012 14:42 :: adamwillwalker :: Replies: 3 :: Views: 252
A. Situation
--------------------------------------------------------------------------
1. I wanna a pulsed current(1mA, 0mA) to a load resistor(R0).
2. M1, M3 are current mirror pairs.
3. M1 is generating a Vgs1(for 1mA) and M3 is copying a Vgs1 so that M3 can flow current of 1mA.
4. M2 is a switch for shorting and opening between Vg1
Analog Circuit Design :: 06.09.2012 13:20 :: angbong :: Replies: 5 :: Views: 193
there a way to protect the mosfets from saturating using resistors or capacitors?
Due you are under development stage, I suppose you are using a DC regulated power supply, with limit current protection, wright ?
That´s the standard procedure, and if the case, there is no need to do that you are asking.
Power Electronics :: 25.02.2013 11:25 :: andre_teprom :: Replies: 17 :: Views: 317
Hi!
I am trying to build a high power speed controller for a DC motor.
I want to control the motor only to one direction. I decide to use a single mosfet with a mosfet driver as the following schematic
Electronic Elementary Questions :: 17.03.2013 22:32 :: auto_mitch :: Replies: 2 :: Views: 201
Dear friend,
Each mosfet model has its merits and drawbaks, like accuracy or simulation time, thus converting them maybe loss the accuracy.
some programs like @dv@nced D esign Sys. can open all spice format like HSpice or PSpice without any problem like mosfet modeling incompatibility,also this new softs. have a large number of known and (...)
PCB Routing Schematic Layout software and Simulation :: 23.01.2003 11:20 :: goodboy_pl :: Replies: 5 :: Views: 1923
in fact,you problem is not so easy.but if you want low power dispension,maybe mosfet is the only way.you can use four 20V 0.005 oum mosfet parallel,get a very low instance, only about 1W dispension,and four SO8 chip mosfet can work well with about 30 degree temprature warry about others,if you find a error in one power (...)
Professional Hardware and Electronics Design :: 17.02.2003 05:12 :: shanren :: Replies: 12 :: Views: 2696
Thanks for this information
The issue is not about safety only ;but, some of the measurement instruments actually connect their local common point to the ground of the chassis ( the earth) & may not have the ability to compensate the variation of the ground ( which MUST be a stable 0 V ) & we do not have the ability to change this ( or we may ma
PCB Routing Schematic Layout software and Simulation :: 09.03.2003 07:34 :: superluminal :: Replies: 5 :: Views: 1321
hi,can anyone can tell me about how to reduce the rf noise of SMPS?
and a strange problem,a build a smps of about 50w ,24v2a.when it works,sometimes is good,but sometimes it will sent out 100Hz sound noise,i find when this hanpens,the voltage of mosfet drain is not the same as it works well.but sometimes it will be ok after a few seconds,and maybe
Professional Hardware and Electronics Design :: 04.09.2003 09:24 :: shanren :: Replies: 4 :: Views: 1612
Hi.. You could use mosfet drivers which are specifically design to do the job. Linear techbology has very good one for N or P channel FETs.
linear.com
International Rectifier has very good one too..
Makes your work easy and a finished reliable product.
Regards
Professional Hardware and Electronics Design :: 28.12.2003 23:52 :: henrik2000 :: Replies: 25 :: Views: 15290
Consider the DC operating point of both circuits. The second-stage's gate voltage is VDD-|VDS(MP4)|, and approx. equals to VDD-|VGS(MP3)|. This voltage is what the left-hand figure needed. In the right-hand figure, however, the Vgs of the second stage's mosfet will be much greater than Vthn, and changes with power supply -- VDD. This is not desirab
Analog Circuit Design :: 06.01.2004 08:42 :: Hughes :: Replies: 5 :: Views: 1099
sorry .. how large leakage current about your powerMos ??
as I know power mosfet Ids =6A Cgs=1000p leakage = 0.1ua (Vds=0
Vgs =20v) or SI2031 have large leakage current ..
Analog IC Design and Layout :: 28.05.2004 03:20 :: andy2000a :: Replies: 7 :: Views: 1697
What about using mosfet to do the design because they are low power consumption? Any drawback?
Also, How does the value of each of the bias resistor affect the circuit? What is recommended value for the pull-up resistor?
Electronic Elementary Questions :: 20.07.2004 23:52 :: skyglin :: Replies: 17 :: Views: 7953
HI
also i think that as a result of the switching signla a logical heating may happen here.
this also happens while driving the mosfet gate .
u should select the type and the rating of the resistor carefully .
i can not remember the address but still having the file
see the attachment
OK , thanks .
Professional Hardware and Electronics Design :: 04.04.2005 13:41 :: HINDI :: Replies: 6 :: Views: 2034
I have a mosfet that controls a dc motor. Without snubber, mosfet gets hotter and hotter. With a diode snubber, this time diode gets hot. I used a slow diode. I'll also try a fast diode but i wonder that does snubber helps to reduce the dissipated power or does it take it from mosfet onto itself? I mean, must i use a huge diode or can i (...)
Professional Hardware and Electronics Design :: 03.09.2004 08:25 :: seyyah :: Replies: 7 :: Views: 5381
I have a 24V dc motor. I'm driving it using a mosfet by using pwm method which is at 20KHz. I remember that i was able to apply max voltage(I mean i suddenly apply any duty cycle e.g. %50) and the motor was responding it before. I don't know what happened but know the motor doesn't start normally. It starts if i connnect a diode across the motor t
Robotics and Automatics Forum :: 06.09.2004 23:53 :: seyyah :: Replies: 9 :: Views: 2102
that was exactly the answer i was thinking of when u asked for high side driver. but then i saw your circuit. i think you will run into a couple of problems when trying to use that king of circuit normally reserved for power switch application and not high side drive of a half bridge. half bridges are usually used because of high power and high
Hobby Circuits and Small Projects Problems :: 18.09.2004 02:34 :: Mr.Cool :: Replies: 16 :: Views: 19587
It looks like you are making a constant current source or current limiter. You will need to use a P type mosfet for the series pass transistor and put the source to the input and the drain to the output.
This is a good situation where SPICE type simulators are very good because you can examine the simulated currents. PSpice has a free studen
Electronic Elementary Questions :: 04.10.2004 06:29 :: flatulent :: Replies: 3 :: Views: 2732
If you use normal enhancement nmos (nmos outside nwell) as cap, the S, D and B terminals should be tied to VSS. Only the G terminal can be connected to other node. If you want a mos cap not connected to VSS, please use mosfet in nwell -- either nmos in nwell or pmos in nwell. On the latter case, the mosfet should be properly biased.
Analog IC Design and Layout :: 14.10.2004 03:37 :: Hughes :: Replies: 8 :: Views: 2363
put a 10 ohm resistor in series with the mosfet gate to reduce ringing and to limit the current in/out of the mosfet during switching.
i heard you mention the word lamp. i am wondering if you are planning on using a mosfet to turn ON/OFF the lamp? be careful how you do this.. lamps are usually AC powered so your (...)
Microcontrollers :: 23.10.2004 03:29 :: Mr.Cool :: Replies: 22 :: Views: 2657
I assume the 'high power' of the DC motor is 'DC power supply'. If it's DC power supply, probably you could use mosfet or IGBT to replace the Triac. Can you have that option?
Robotics and Automatics Forum :: 13.11.2004 08:59 :: nicleo :: Replies: 7 :: Views: 5903
i have problem?
i can not design circuit.
i want circuit?
Plese help me
thank.
Electronic Elementary Questions :: 18.12.2004 15:27 :: pops999 :: Replies: 2 :: Views: 1769
Speaking for BSS89 small signal nmos, If I do not use gate resistor then the transistor is more likely to be damaged. I throw away tens of these mosfets to find if the problem realy comes from unused gate resistors...and now I am sure....
Microcontrollers :: 24.12.2004 23:03 :: Free_Will :: Replies: 4 :: Views: 1121
That sounds too weak - I think your transistor is sized wrong. First, 0.6um can't hold up to 18v, it would need to be 2-4um meaning that you should be using sizes nearer to 20/2 rather than 6/0.6. Are these mosfets DMOS or standard CMOS?
Can you PM me - I am interested in this process, I would like to take a look. I can help debug your mosfet
Analog IC Design and Layout :: 10.01.2005 23:23 :: electronrancher :: Replies: 6 :: Views: 958
IRF540 is fine to use at 10V. you do not need a transistor front end.
first remove the 555 timer and see if you can at least turn the solenoid ON. what is the pull-in current of your solenoid? Size your current limiting resistor for this +20% and make sure resistor is rated for continuous power loss (even though you plan on pulsing the circuit)
Electronic Elementary Questions :: 14.01.2005 04:14 :: Mr.Cool :: Replies: 41 :: Views: 18034
The mosfet ratings confuse many people. The current rating of the mosfet tells you what the maximum current can be with the mosfet fully on and the case temp 25°C. Under these conditions, the power dissipation is Pd=Rdson^2*I. For this power dissipation, with the case at 25°C, the junction temperature reaches its maximum permissible, either (...)
Analog Circuit Design :: 18.01.2005 18:42 :: VVV :: Replies: 12 :: Views: 2353
I am wondering to drive high power lamp using mosfet or Relay?
Could anyone explain the main difference between these two schemes?
Thanks a lot!
Electronic Elementary Questions :: 31.01.2005 03:23 :: bluewave :: Replies: 7 :: Views: 3472
The mosfet gate drivers are used to ensure a complete on/off state for mosfets .
Also, if the mosfet is a high side switch the source will be considered as a floating point while it is not tied to the ground , so it is important to ensure that the voltage Between the gate and the source is more than 12 v to avoid the negative temperature (...)
Analog Circuit Design :: 07.02.2005 14:15 :: HINDI :: Replies: 6 :: Views: 7179
You will have to put a transistor inverter after the 2 V to get the swing necessary to drive the mosfet gate. Then you will have to use the opposite 2 V, 0 V signal to turn the motor on/off.
Hobby Circuits and Small Projects Problems :: 16.02.2005 06:15 :: flatulent :: Replies: 4 :: Views: 1782
Hi,
After reading the data sheet for the LCD i can try to answer your questions:
1.does it mean that i can't reset LCD when it's power is connected and middle of using it ?
No you cant. The rest can happen only when you power the LCD. Like your PC, you cant generat a complete reset while the computer is runing.
2. if so
Microcontrollers :: 05.03.2005 16:43 :: gidimiz :: Replies: 3 :: Views: 1138
Hi,sandusty
I think the difficulty is the SDF is used for STA and other post simulation,it is from the netlist and library.
Unlike analog RC extraction (they can get RC parasitic form mosfet level netlist and layout),it need the timing information in your library,unfortunately,that is what you haven't.
So if you want to go on,maybe you can do
ASIC Design Methodologies and Tools (Digital) :: 31.03.2005 04:15 :: flyankh :: Replies: 5 :: Views: 796
I'm trying to drive a mosfet using ir2110. I tried a lot of thing but still couldn't get an output from the 2110. Both high output and low output doesn't give a voltage output. They ara always at zero. What may be the problem? Please help because i'm stuck badly.
Professional Hardware and Electronics Design :: 28.03.2005 20:23 :: seyyah :: Replies: 2 :: Views: 1508
hi i'm newly joined member in this forum... doi ng my project in m.tech.. well i'm building a hardware circuit for 60 watts AC-DC 1-φ buck converter... the problem is with the mosfet gate driver. i'm making use of ir2110 driver... as i want to isolate the pulse given to the mosfet so i'm giving pulse only to the high side drievr... (...)
Analog Circuit Design :: 14.04.2005 13:52 :: satyasree :: Replies: 0 :: Views: 1442
i am design a LNA with ADS recently, now i need to analyze the Fast, Slow, and Typical case of the mosfet in order to find out impact of these three case on the total
LNA circuit. I am using TSMC0.18 process. But I do not know the details of Mento Carlo analysis setup in ADS. i wonder who will tell me or give me a document about Mento Carlo analy
Software Problems, Hints and Reviews :: 11.05.2005 15:14 :: wizardyhnr :: Replies: 0 :: Views: 490
You should duplicate the suggested circuitry in the data sheet
and remove the BJT additions. In your present design the BJTs are not biased properly and do not do any switching. They are just extra networks between the IR chip and the mosfet.
Professional Hardware and Electronics Design :: 21.05.2005 19:25 :: flatulent :: Replies: 8 :: Views: 3546
Hai
I want to know which are the capacitances that wll be effected by scaling of a transister.What are the new capacitances that will come into picture.
Analog Circuit Design :: 24.05.2005 21:54 :: venkata :: Replies: 7 :: Views: 1299
Your gate must be positive against the source. Thinking upper sides, source side of the mosfet is at bus voltage when it is open. So if your bus voltage is say 48V then your gate must be 60V or so according to the ground and 12V (If your gate needs 12V to be driven) according to the source. To accomplish this, you need a bootstrap circuit or an iso
Analog Circuit Design :: 31.05.2005 20:18 :: seyyah :: Replies: 1 :: Views: 578
It costs to use Cadence,thanks a lot for your reply.during the time, I did much simulation,and got a much better result,the CMRR is 81dB,and 3dB frequence is about 3Mhz ,here is the spice file.we can have more discuse on this topic.
Added after 52 seconds:
* SPICE netlist written by S-Edit Win32 10.00
* Wr
Analog IC Design and Layout :: 21.06.2005 12:53 :: nivico :: Replies: 13 :: Views: 1473
The problem is of course that you cannot drive the mosfet into saturation.
The eaiest thing to do is use a P-ch device and reverse the signal of the PWM.
Else, use a charge pump to generate a voltage about 8-10V higher than the input voltage and power your controller from that voltage. That way you will be able to always drive the (...)
Analog Circuit Design :: 03.06.2005 07:18 :: VVV :: Replies: 9 :: Views: 1714
Anybody can tell me the meaning of voltage headroom, is there any relationship with voltage swing, thank you very much!
Analog IC Design and Layout :: 24.06.2005 11:34 :: abcyin :: Replies: 3 :: Views: 1222
You should never connect microcontroller pin(s) to a device such as a motor .. These pins are designed to drive buffers, sometimes directly LEDs or CMOS/TTL gates, but are not desgned to cope with inductive loads.
After all, they can "consume" only some mA of current in sinking configuration and produce next to nothing in source configuration ..
Electronic Elementary Questions :: 27.06.2005 13:52 :: IanP :: Replies: 8 :: Views: 2562
How can we determine that a mosfet gate draws how much current and choose a proper mosfet driver?
Professional Hardware and Electronics Design :: 04.07.2005 18:53 :: seyyah :: Replies: 10 :: Views: 10435
hi,
i want to design a h-bridge to control a dc motor. (24V ~15A). i chose mosfet as power switching element. do i need to use mosfet driver component or not?. if i need why? isn't it enough to drive a mosfet drectly using dc voltage.
Electronic Elementary Questions :: 05.08.2005 15:44 :: hakan :: Replies: 5 :: Views: 1627
you can drive step motor with mosfet as like as bjt ,when a signal like as signal come from pc or micro the mosfet must be on and the signal can travell throw this part like switch or relay it is very nice !! isn't it?
you must bais mosfet for larg signal.. it is very easy easy than bjt.
Analog Circuit Design :: 15.08.2005 04:48 :: haerifar :: Replies: 5 :: Views: 5081
I have an IRFP350 commuting 340V to a 71Ohms load. The mosfet need dissipate 28W. If I fix the transistor to the case, this quantity of power can be dissipated, but the problem is that this case is accessible by the operator (the case is electrically connected to the earth terminal).
Any body can tell me what kind of insulator can I use in order t
Analog Circuit Design :: 04.09.2005 17:15 :: bomba :: Replies: 6 :: Views: 893
Hi,
In Razavi, problem 2.13 (page 40):
" The transit frequency of a mosfet is defined as the frequency at which the small-signal current gain of the device drops to unity while the source and drain terminals are held at ground".
How can there be current in the transistor when Vsource=Vdrain=0V?
As far as I know, this is defined as trio
Analog Circuit Design :: 26.09.2005 19:47 :: sharas :: Replies: 5 :: Views: 6656
Hi,
i am simulating this circuit using M*I*C*R*O*C*A*P VII and i am not getting any results.
In my opinion it seems to work, but that's not what i am getting.
I have to build a simple power amplifier to output AC current to a capacitive load, so i decided to use mosfet as output amplifiers (operating in class B).
I believe that the OPAM
Electronic Elementary Questions :: 05.10.2005 00:36 :: mcoster :: Replies: 6 :: Views: 635
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