Basically the wider the width
more current will pass through mos
on the other hand there is an increase in parasatic capacitance.
If you say if an Nmos
x take t psec to discharge a load capacitance then a Nmos
xx>x will take tt
Electronic Elementary Questions :: 24.03.2006 02:07 :: vikadik :: Replies: 6 :: Views: 1301
Thank you for your reply .
Yes it is 12.5MHz for the peroid 80ns, it is my error.
Sorry I could not provide a schematic for you.
In my project, I want to use a mos campacitor connecting one input node of the comparator to attenuate the noise from the other input node. So I prefer to minimize the mos width and (...)
Analog Circuit Design :: 12.10.2006 23:51 :: jluhzw :: Replies: 2 :: Views: 552
i cant post the link but , if you search for
ECE-E432 Microelectronics II
Drexel University Electrical & Computer Engineering
Lab 1. - mos Device Characterization
that lab should be helpful
Analog Circuit Design :: 08.09.2010 23:39 :: GhostInABox :: Replies: 9 :: Views: 4611
this will act as a W/2L mos transistor (in sat region).
Analog IC Design and Layout :: 25.04.2007 15:59 :: hr_rezaee :: Replies: 3 :: Views: 1204
I am a beginner in the VLSI layout design and confussed in the lambda based rules. For example if I have a 0.5u Cmos process based rules, how the width of Pmos and Nmos transitors are derived?
Analog IC Design and Layout :: 21.10.2007 19:24 :: berko3000 :: Replies: 3 :: Views: 2720
Look into a design manual. They usually extract models for specific W and L of mos device. Those are the "exact" values. Then they include scaling which is theoretical approximation. I use max W as 10um and if I need bigger size I use parallel multiple. Then you can use virutaly any W you want.
L is the litography limit for the technology. For d
Analog IC Design and Layout :: 22.10.2007 17:44 :: Teddy :: Replies: 3 :: Views: 973
If I make a mos transistor's width longer than its length in an IC circuit, is there any drawback by this way, especially in the layout level?
Analog IC Design and Layout :: 15.11.2007 02:32 :: abcyin :: Replies: 26 :: Views: 4787
In what way mos overtaken BJT ??
plzz explain briefly
One thing, that it's easier in integration and fabrication as its geometry is much simpler than BJT, and with nowadays short device lengthes, it can acheive high speed as BJT in the past.
ASIC Design Methodologies and Tools (Digital) :: 02.04.2008 06:57 :: ahmad_abdulghany :: Replies: 2 :: Views: 3960
Hi, can anyone tell me what the minimun channel length for a mos transistor for AMS 0.35um process, and why follow the LAMBDA rule for width and length for cmos transistor.
Analog IC Design and Layout :: 25.08.2008 11:31 :: Advark :: Replies: 7 :: Views: 2183
We often use this type mos as large resistor. I wonder if there are some rules in thumb for using this "inverse W/L ratio" transistor.
Analog IC Design and Layout :: 04.11.2008 10:19 :: luobo :: Replies: 0 :: Views: 537
I hope this link will help you a bit.
Analog IC Design and Layout :: 29.05.2009 05:29 :: fixrouter4400 :: Replies: 3 :: Views: 1386
The more detailed you make the simulation (you should simulate this) the more accurate your resistance calculation. Metal 1 resistance usually overwhelms all the other metal resistances because it is in narrow stripes on the drains and sources. One half of the mosFET has all the metal 1 strapped with vias to metal 2, the other half is a long metal
Analog IC Design and Layout :: 27.09.2009 17:10 :: snafflekid :: Replies: 2 :: Views: 1261
For simple rectangular mos transistors, it's easy to identify width and length depending on direction of current flow.
If you've complex irregular mos transistor (not like a spider :D but mostly like a rectangle having many glitches from one or both sides), is there a scientific method in this case (...)
Analog IC Design and Layout :: 15.04.2010 16:36 :: ahmad_abdulghany :: Replies: 2 :: Views: 715
is there any problem if we do not keep the drain and source areas same width and length like emitter and collector in bipolar junction transistor????????
Analog Circuit Design :: 13.05.2010 08:34 :: lokesh garg :: Replies: 0 :: Views: 362
I have kept Nmos width constant and sweeping Pmos width. Results show that fall time is increasing drastically.
What are the reasons for the increase of FALL TIME?
PLD, SPLD, GAL, CPLD, FPGA Design :: 20.09.2010 03:14 :: Somashekhar :: Replies: 5 :: Views: 863
In a typical inverter, Nmos pulls the output to low, while Pmos pulls the output to high. To increase the threshold, you need to increase the strength of the Nmos and/or reduce the strength of Pmos. The strengh of a mosFET is decided by its W/L (width/length) ratio. The (...)
ASIC Design Methodologies and Tools (Digital) :: 31.01.2011 17:39 :: ebuddy :: Replies: 6 :: Views: 2269
Can any one tell, whether the line width and the channel length are same!
what is meant by line width of a mosfet? and please provide me some examples!
Electronic Elementary Questions :: 02.02.2012 07:44 :: vinaychinni :: Replies: 1 :: Views: 267
Where to define the V-I characteristics of a new created device\part.
e.g., I have to use mos and I created my own part using ?NEW PART? in ?USER DEFINED PROPERTIES? i added new property width, length but where I have to give the characteristic equation which defines the relation of voltage, current, W/L ratio and other parameters.
Software Problems, Hints and Reviews :: 16.02.2012 09:57 :: nsrknt :: Replies: 0 :: Views: 380
for nmos transistor
the on resistance Ron is given by the equation
Rtransistor =Lg0/(width* mu *COX*(VDD-VT0))
i use the following values
Lg0 17.5 nm -> .0175 micro meter
width 140 micro meter
this make w/l =8000 which i think very reasonable
VDD 1 volt
VT0 0.18 volt
from my model i found COX 3.137727e-14 farad per Micro (...)
Microcontrollers :: 24.03.2012 17:23 :: Eman kamel :: Replies: 2 :: Views: 858
the minimum length cannot be used in the analog design circuits, usually you need minimum of 2*min L and that because of :
1. minimum length has worst case matching
2. has higher channel length modulation that we never like since it will degrade the mos transistor output impedance and hence degrade the design of the (...)
Analog IC Design and Layout :: 04.10.2012 16:42 :: Junus2012 :: Replies: 4 :: Views: 383
So I need to make sure a mos Cascode along with other devices in one (vertical) arm of the circuit lying between VDD and GND doesn't collapse under all corners.
For this i usually make sure the VDS (or the VCE in Biploar) doesnt go below say 250mV (or about 300mV in Biploar) in a nominal run, say a dc sweep over temperature.
I see ther
Analog Circuit Design :: 01.11.2012 06:08 :: manrajgujral :: Replies: 1 :: Views: 172
1. Which skill function can change a mos' length and width in the schematic?
2. Whcich skill function can be used to flatten all layout database ?
3. Which skill function has sizing function for layout database?
4. Is there a tool can follow the design rule to automatic sizing layout database?
ASIC Design Methodologies and Tools (Digital) :: 11.08.2004 06:09 :: Jerry Yau :: Replies: 0 :: Views: 761
1. measure the open loop gain. the most important parameter is the input offset voltage. check on these a rule of thumb, the length of the mos is 2-5 times bigger than the min length. for the width, consider the matching and the current mirror.
Analog IC Design and Layout :: 18.08.2004 21:22 :: Edward_2288 :: Replies: 10 :: Views: 2803
There are other ways to calculate W/L for active loads. Usually designers choose Vdd/2 as Vocm and for a desired symmetric output swing you can calculate the voltage headroom over these active loads. as a rule of thumb we often choose veff of each active device (if we use two stacked mos trs as the active load)
Veff = (Vdd/2 - outswing/2)/2.
Analog Circuit Design :: 11.05.2005 08:56 :: ezt :: Replies: 3 :: Views: 1004
I use BSIM3v3.3 mos transistor models for RFIC design. BSIM 3v3.3 does not include a substrate network but just a drain-bulk capacitance which may be insufficient at high frequencies. I decided to use a grounded substrate contact surrounding the transistors
to reduce the substrate resistance. The distance between the transistor and the cont
Analog IC Design and Layout :: 18.05.2005 09:42 :: estradasphere :: Replies: 3 :: Views: 723
Why does the threshold voltage of a mos increase when we increase the L of the transistor?
Analog Circuit Design :: 27.06.2005 17:34 :: aryajur :: Replies: 3 :: Views: 1133
If we have 2 mos with exactly the same VDS and VGS, the same lengths, but widths in the ratio say 25:1. Why shouldn't the currents be in the ratio 25:1? I am asking this because simulations don't show the current ratio to be 25:1.
Analog IC Design and Layout :: 28.07.2005 14:54 :: aryajur :: Replies: 12 :: Views: 1368
yes if you want to design IO by yourself , first you shold konw some analog knowledge, layout design method is also needed, ESD and ESD protect circuit and Latch are necessory, if the foundry are detemined, normally foundry will recommend you the ESD protect circuit structure and detail design parameter, such as, mos length,width, resistor, (...)
ASIC Design Methodologies and Tools (Digital) :: 25.08.2005 20:50 :: tarkyss :: Replies: 2 :: Views: 995
If you've done IC layout, be it Analog or Digital/ASIC, you will wonder how to calculate the cell area. Well, here are some rules from which you can calculate the area...
1. Resistor Area:
Ar = 1.2RWr(Wr + Sr) / Rs
R = Desired Resistance
Rs = Sheet Resistance
Wr = width of the Resistor
Sr = Spacing between
ASIC Design Methodologies and Tools (Digital) :: 12.11.2005 02:32 :: vlsi_whiz :: Replies: 0 :: Views: 1380
Usually mos transistors in triode region are used for switches. Depending on the configuration, either an Nmos or a Pmos or a combination of both is used.
The length of the mos is kept minimum to reduce parasitic capacitances. Depending on the application, the width is adjusted. (...)
Analog Circuit Design :: 01.03.2006 17:23 :: lavitaebelle :: Replies: 6 :: Views: 883
hi, If you want to analyse the mismatch of Band gap, the mismatch parameters from the foundry are needed.
For example, the 3.3V Pmos Vtsat mismatch parameter is 4.9mV*um. If you want to know the Vt mismatch of a Pmos current mirror with size of W=10um, L=5um, the Vt mismatch equals to 4.90mV*um/sqrt(10um*5um)=0.693uV.
Normally the (...)
Analog Circuit Design :: 31.05.2006 02:01 :: lunren :: Replies: 6 :: Views: 1498
what is meaning by short channel of mosfet
Analog Circuit Design :: 20.05.2006 08:29 :: hamdy :: Replies: 1 :: Views: 571
that was my question.. How is area occupied by the mos calculated given the spice model
ASIC Design Methodologies and Tools (Digital) :: 08.06.2006 02:56 :: Resistance :: Replies: 7 :: Views: 1602
just be curious how to choose the w and l of a mos fet
example，in the pic，a larger l and smaller w campared to lower one is chosen to produce a lower common mode output voltage(hen
Analog Circuit Design :: 19.10.2006 13:00 :: Youncen :: Replies: 2 :: Views: 605
Hi all, I have read a paper mos Operational Amplifier Design? A Tutorial Overview by P. R. Gray recently, but there is something I can't understand very clearly. So I think I need your help. Here it is:
For constant drain current decreasing either the channel length or width results in a decrease in the gain, the latter because of the fact (...)
Analog IC Design and Layout :: 03.12.2006 22:01 :: cherryic :: Replies: 1 :: Views: 512
I also had the same situation like you.But My circuit at mos level,so I checked the Lenght of transistor,and I found it not valid with Model. I think you should check your circuit again(it maybe run in Winspice but not in T-spice)
Analog IC Design and Layout :: 02.01.2007 20:58 :: anhtuan :: Replies: 4 :: Views: 1403
The bias will change when VDD, corner, temperature and resistor variation.
I don,t know your application, So I cann't comment more about design.Maybe you don't care the bias variation, and the slew rate symmetry.
"but different width is okay to apply in the layout design? "
You can let the width of large mos and small (...)
Analog IC Design and Layout :: 08.06.2007 03:51 :: jerryzhao :: Replies: 6 :: Views: 1175
How does dracual LVS extract channel width and length of mos in layout? and, if i want to change the formula for calculating the value of W or L, what should i do?
It is always easy for calibre lvs users to find the expression and revise.
Thanks in advance
Software Problems, Hints and Reviews :: 27.07.2007 02:51 :: yann_sun :: Replies: 1 :: Views: 610
How does dracual LVS extract channel width and length of mos in layout?
I mean how the "W=** L=**" expression is obtained by dracula lvs run. This expression is locating on the right side(layout devices, nodes and parameters) of .lvs file? and, if i want to change the formula for calculating the value of W or L, even those of (...)
Analog IC Design and Layout :: 27.07.2007 03:08 :: yann_sun :: Replies: 0 :: Views: 464