BackendVLSI

 1.Lambda-based design rules? Ans.  Layout or Design Rules: Two approaches to describing design rules:  Lambda-based rules : Allow first order scaling by linearizing the resolution of the complete wafer implementation. To move a design from 4 micron to 2 micron, simply reduce the value of lambda. Worked well for 4 micron processes down to 1.2-micron processes.

What are lambda based design rules? What is nm in 10nm technology node? Do you know about under bum density? Any prior experience of PnR? How do you import design in PnR? Why ID layers have been given in lower nodes (10nm)? Why nwell continuity is required? Have you done scripting? Can you write an algorithm? What is drive strength? Why the industry is moving towards lower technology nodes like 7nm or 5nm? What are challenges seen in lower technology node? What are the difference between 45nm and 65nm routing rules? any new rule in the 45nm? Why foundry define DRM, routing rules? What is stack means? How many types of metal layers are in 65nm/45nm? Why metals are of different thickness? Why thin metal are in lower position and thick metals are at upper position in a defined Stack? What is the need of several types of metal layer in a design? What do you mean by RDL layer? Why it requires? How many types of routing? What is the sequence of that? Power is routed first or clock is routed ...

  1. specification :   This is the first stage in the design process where we define the important parameters of the system that has to be designed into a specification . 2. Behavioural description :   T his is the stage where the design team and verification team come into the cycle where they generate RTL code using test benches. This is known as   behavioral simulation . 3 . RTL description :  RTL code is a set of code that checks whether the RTL implementation meets the design verification) is done in HDL, a lot of code coverage metrics are proposed for HDL. 4. functional verification :  Functional Verification is the process of verifying the functional characteristics of the design by generating different input stimuli and checking for correct behavior of the design implementation. 5. Logic synthesis: the process of converting get level netlist with their logical connectivity for simulated RTL code. In this synthesis, we can check not only functionali...

 

 For unsigned number computations, no need to add one more additional bit for computations or calculations. But, while doing signed numbers computations (-ve numbers), Then we need to add one more bit for signed representation. Then the total area, power, the cost will be more, due to increasing of area. To solve this problem, the alternate method is "complements". The complement is used for representing ' the negative decimal number in the binary form '. Different types of complement are possible of the binary number, but 1's and 2's complements are mostly used for binary numbers.  Generally, they are r's and (r-1)'s complement is possible, but                                                                                r---> should be is even number  Addition rules: su...

  The  Gray Code  is a sequence of binary number systems, which is also known as  reflected binary code . The grey code is widely used in security applications, so it is called security code . the grey code is also called unit distance code because the only one-bit position will change between any two nearby grey codes. The gray code is a very light weighted code because it doesn't depend on the value of the digit specified by the position. This code is also called a cyclic variable code as the transition of one value to its successive value carries a change of one bit only. In this code, two consecutive values are differed by one bit of binary digits. Gray codes are used in the general sequence of hardware-generated binary numbers. These numbers cause ambiguities or errors when the transition from one number to its successive is done. This code simply solves this problem by changing only one bit when the transition is between numbers is done. In Grey code ,we need t...