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Friday, April 9, 2010

Introduction....




May Peace and blessings of the Almighty be upon you...

Please Note:

Before starting this post, one important thing I would like to address. In this post and future, you may come across a lot of new technical terms. All I can say is, just skip them if you can't understand and continue reading. Over the period of time when we see detailed explanation of them you will be able to understand and relate to previous posts. Insha Allah…   

Lets go ahead now...

1. What does VLSI mean?

VLSI stands for Very Large Scale Integration. As the name suggests, when a large number of transistors (say for example greater than 10,000 transistors) packed in an Integrated chip then it is said to be following VLSI technology. To be more precise, making an IC with large number of transistors is called VLSI. Today’s sophisticated Integrated Chips have millions of transistors inside them.

But I used to say, VLSI means making a Simple IC (also), because if we can’t understand how a simple IC is been made and then how come we learn about multi-million transistor design? So let us start with a simple IC, how it is been designed and made, and then focus on packing multi-million transistors.    

But VLSI has another side to it also, configuring programmable devices such as PLDs (PLAs, PALs, PROMs and CPLDs) and FPGAs are also considered to be a part of VLSI.


2. Why is it so?

As far as I am concerned there are two major reasons behind it.

a) Motive of both of them is the same (or in other words, the results they try to achieve is the same).

For example, let us assume that we need a EX-OR circuit; there are two ways of getting it. The first, get the EX-OR circuit by designing (using CMOS processes, layout etc., which we will see later) and fabricating. The resultant IC from fabrication contains EX-OR circuit.

The second, take a programmable device, describe the behavior of EX-OR circuit (by writing codes in VHDL/Verilog HDL or through schematic) and dump it in the programmable device. Now your programmable device will work as EX-OR circuit.     

Since both of them produce same result, Programmable devices are said to be part of VLSI.

b) The approach towards the Motive is almost same.

For example, when I say, write the code and dump (Configure) it in the programmable chip, that does not mean there are only two steps. In-between writing the code and dumping, there are other steps need to be followed like synthesis, placement and routing etc (which we will see later). These steps are called Design Steps. 

Similarly to make an IC on our own, we need to follow certain steps (Design Steps). These steps are almost similar to the steps that we follow in configuring programmable devices.

Since both of them follow similar steps to achieve their motive, programmable devices are said to be a part of VLSI technique.

There may be some other reasons also like prototyping etc., which we will see later, Insha allah…


3. Where does VLSI techniques used?

Just look around you. Look at the computer you are using, look at the IPOD you are using, look at the mobile phones you are using, etc etc. They all contain ICs packed with millions of Transistors. You can't imagine electronic products without VLSI techniques.  


4. Why VLSI is so important?

By this time you would have understood that. If todays's world heavily dependent on state of the art Electronic goods, then those goods heavily depend on sophisticated Multi-Million transistor ICs. Thus the importance. You can't just skip VLSI techniques and claim to be a better Electronics Engineer.


5. Is VLSI a kind of course which one needs to learn separately?

It depends on the educational institution one studied/studying. If you are from the stream of Electronics, Electrical and Instrumentation, then you already got a glimpse of it in your college days. Or if you are a student then you are learning it now. 

Most of us learned about or learning about terms like CMOS, ASICs, Lambda based rules, digital electronics, HDLs, Layout etc., which will obviously lead to VLSI. 

Having said that, VLSI tools could not be found in most of the educational institutions, primarily due to cost involved with them. In that case an outside course will help a lot. 


Let me finish by saying this, VLSI is not at all a complex thing to learn. It is so cool and fun. That is what I will try to do in future posts, ie. presenting VLSI in the easiest way possible. Insha Allah...

Do send in your comments if you face any difficulty in understanding...

God knows best...

Thanks,


Your brother,
Aashiq Ahamed A

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