Current Density of metal..

How to Find the current density of metal layer?

Margin between short channel and long channel MOSFETs

For values of channel length, MOSFET falls into short channel category?

Importance of top metal layer

Do you know the reason??
Why the top metal layer is wider than other lower metals in semiconductor process?
-->
      Top Metal Layers (like M7 , M8 , M9 , ...) are made Wider to reduce the Resistance.

But,why only top metal is wide??

If M1,M2,M3,M4,M5 are also wide, All metal would have low resistance?
          Lower metals are kept for nets connection that are not conducting heavy current. Top metals are for carrying heavy currents like clock,vdd,vss etc. If we have wider metals in lower levels , we will face issues due to heavy capacitve effects of wide metals. And increasing metal width will increase the area of the cell due to the requirement of more routing area.

"High-k" The next generation transistor materials.

Have a look at the Intel's new reseach.

http://www.intel.com/technology/silicon/high-k.htm

Usefull Linux commands

1.copy a file from source location to destination:

cp source destination:

Ex: cp /root/qwertyt/doc.ppt  /root/qwertyt/test2

2.Lists the files in the present directory

ls

3.Lists the last few files created
ll -lrt 

4.Change Directory

cd

Ex: cd test2

5.Make Directory:

 mkdir

6.Remove file :

rm -rf filename

7.Change access permissions 

chmod -Rf 755 directory

8.Displays first n lines

head -n

Ex: head -5 test5 9.Displays last n linestail -n

Ex: tail -5 test5 

10.Print Working Directory:

pwd 

11.cat:

Display the contents of a file

12.Clear terminal screen:

clear

13.Compare two files: 

cmp 

14.Display or change the date & time:date 

15.Display the differences between two files:

diff

16.Exit the shell:

exit

17.Search file(s) for lines that match a given pattern:

grep

18.Print user and group id's;

id

19.List active jobs:

jobs 

20.Stop a process from running:

kill

21.Help manual:

man

22.Rename files;

rename

23.Reverse lines of a file:

rev

24.create a new file:

touch

PERL: SHORTCTUS

1. <STDIN> Command is used to scan the inputs.

   Ex:

$a=<STDIN>;

You can shorten this command as shown below,

$a=<>;

2. Consider an example,

print “Enter a number \n”;

$a=<STDIN>;

if($a=1)

{

print “..............................\n”;

}

You can shorten the above script as shown below,

print “Enter a number \n”;

if(<>=1)

{

print “..............................\n”;

}

No need to save the scanned inputs in a variable, You can compare the scanned inputs directly.

3.Use EOT command to print multiple lines.

Ex:

print << 'EOT';

ENTER 1 for .....................

ENTER 2 for .....................

ENTER 3 for .....................

ENTER 4 for .....................

EOT

MAGIC : DOWNLOAD & INSTALL

Download VLSI LAYOUT TOOL "MAGIC" FOR UBUNTU:

[DEBIAN FILE]

http://tuxmaniac.com/work/packages/magic/magic_7.5.129-1_i386.deb

After downloading, double click on it to install...

NOTE:You can download ngspice from UBUNTU software centre.

LAPTOP TIPS by Venkatraman

LAPTOP TIPS

• Never keep laptop on softmaterials like bed or on any clothes. The reason is that processor fan will not get ventilation which results in processor failure as well as battery life will be reduced.

All ways keep laptop on hard surface..!

• Never put your laptop into the bags without turn it off completely(standby is also not allowed).
• Do not bend the laptop power cable and also always keep the battery charger in ventilated place whicle charging.

These suggestions may be rediculous but very important for long life of your system.

=====>For circuit enthusiasts only.

Automatic Laptop Power dis-connector.

It is really good practice to disconnect the laptop power cable after the use. However many times we (I) forget to do so. Here is a simple circuit which automatically connect or disconnect the laptop to main AC plug.

The automatic circuit shown in the below image needs hardly few electronic components. Please make sure that proper teminals are connected from USB cable to relay coil. Any wrong connection can destroy the laptop USB PORT.

The details of connection is shown in above image. I am using this circuit from last 6-months. If you are interested do this one and if you need any assistance please contact any time.

Regards,
Venkatraman.

venkatramanhm@gmail.com

Ubuntu...! One of the best OS...!

The Ubuntu is one of the most competitive OS(operating system) for Windows. I love Ubuntu because of its simplicity. It comes with thousands of application and that too absolutely free!!. No virus problems...! No drivers needed..! No payments of any thing.Install in half an hour and enjoy 365+365+...... days...!

For engineers, OS like Ubuntu is really great gift. Any thing can be automated,anything can be added any instant of time. For example the circuit simulator like LTSPICE work nicely under wine. Ngspice and other circuit simulator also available. The scilab and octave are equivalent to matlab. There are many things to explore. There are thousands of application.

If you have interest, please go to application---> Ubuntu software center and search for all kind of application.


I heartily congratulate the ubuntu community for such OS.

Universal Logic : Mux to Logic gates conversion

1. Designing an Inverter using 2:1 MUX.

2. Designing an AND Gate using 2:1 MUX.

3. Designing an OR Gate using 2:1 MUX.

4. Designing an XOR Gate using 2:1 MUX.

5. Designing an XNOR Gate using 2:1 MUX.

Why the lines of force in an electric field start at the +ve charge and terminate at the -ve charge?

Find the answer at :




http://www.physlink.com/Education/AskExperts/ae245.cfm

LVCMOS

LVCMOS

---

Low Voltage Complementary Metal Oxide Semiconductor (LVCMOS)

 is a low voltage class of CMOS technology integrated circuits.To obtain better performance and lower costs, semiconductor manufacturers reduce the device geometries of integrated circuits.With each reduction the associated operating voltage must also be reduced in order to maintain the same basic operational characteristics of the transistors. As semiconductor technology has progressed,LVCMOS power supply voltage and interface standards for decreasing voltages have been defined by the Joint Electron Devices Engineering Council JEDEC for 3.3, 3.0, 2.5, 1.5, 1.2 and 1.0 volts.

CMOS inverting tri-state buffer

 ------------------------------------------------------------------------------------

The inverter on the left is required to generate the negated value of the 'enable' input signal. (It can be removed if both the positive and negated value of the 'enable' signal are available from external circuitry.) As shown here, the upper p-channel transistor (driven by the enable input) and the lower n-channel transistor (driven by the inverted enable signal) are conducting whenever the enable input is low. In this case, the inner two transistors are supplied with VCC and GND and behave like a standard inverter. As a result, the tri-state buffer output is the inverted of the data input A.When the enable input is high,both outer transistor are non-conducting, and the tri-state buffer output is floating ('Z').

  nENA  A  | NTRI
 ----------+------
     1  *  | Z  (floating)
     0  0  | 1
     0  1  | 0

The Tri-state Buffer is used in many electronic and microprocessor circuits as they allow multiple logic devices to be connected to the same wire or bus without damage or loss of data. For example,suppose we have a data line or data bus with some memory,peripherals, I/O or a CPU connected to it. Each of these devices is capable of sending or receiving data onto this data bus. If these devices start to send or receive data at the same time a short circuit may occur when one device outputs to the bus a logic "1" the supply voltage,while another is set at logic level "0" or ground, resulting in a short circuit condition and possibly damage to the devices.Then, the Tri-state Buffer can be used to isolate devices and circuits from the data bus and one another.If the outputs of several Tri-state Buffers are electrically connected together Decoders are used to allow only one Tri-state Buffer to be active at any one time while the other devices are in their high impedance state.

Tristate Buffer

Tristate buffer

Schematic of the standard cell "buff121" with device sizes in lambda.

Layout of the standard cel

--------------------------------------------

--------------------------------------------

--------------------------------------------

web link : http://www.hpc.msstate.edu/mpl/distributions/scmos/scmos_doc/cells/buff121.html