In this article, we are going to discuss the input files required in various stages of pnr and signoff. We can categorise the set of inputs into two parts, one is mandatory and the other is an optional set of inputs. A. Place and Route stages: I. Pre Placement Stage Gate level netlist Logical Library … Read more
Before starting this article, I would like to say this topic is highly sensitive and we are not supposed to reveal any foundry data. So Instead of making comments on any data which you know and I have not given here, you may mail me along with the reference link. The purpose of writing this … Read more
One scripting language without which it will be very difficult to survive in VLSI Industry, that would definitely be TCL (Tool Command Language). TCL is widely used everywhere in the VLSI industry because many tools are based on the tcl. We can directly interact with the tool using tcl CLI (Command Line Interpreter). It has … Read more
Code: CDN4Y072021PD Experience level: 4 Year Profile: Physical Design Engineer 1. Introduction and physical design experience 2. What major differences have you observed in the 7nm and 14nm process nodes? 3. What is the functionality of this circuit? (He drawn schematic in paint) 4. Do you think, is there any issue with the … Read more
The flip flop is the most commonly used sequential element in any ASIC design, especially the D-type flip-flop. In the D flip flop, the D indicates delay, which means the output is a delayed version of input D. Whereas a latch is the simplest and a basic sequential element. In general, there are two latches … Read more
The tie cell is a standard cell, designed specially to provide the high or low signal to the input (gate terminal) of any logic gate. The high/low signal can not be applied directly to the gate of any transistors because of some limitations of transistors, especially in the lower node. The limitation will also be … Read more
Low power ASIC design is the need of the hour, especially for hand-held electronics gadgets. In all hand-held products, the customer demands more battery life. This could be possible only if our SoC (System on Chip) inside the gadget consumes lesser power. There are various low-power design techniques that are being implemented the reduce the … Read more
Code: EXIM4Y062021PD Experience level : 3 years Brief Introduction and major projects? Tell me the most challenging part of your recent project How does the lockup latch help to fix hold violations? If we add a lockup latch, it might violate the setup? How will we fix it further? How did you … Read more
Code: CDN5Y062021PD Experience level: 5 Years For Application Engineer What are the major differences between 7nm and 12/14nm technology nodes? What are the new DRC rules in the 7nm technology node? What is the via-piller? What is double patterning? How many layers have double patterning in the 7nm node? How … Read more
Placement is a very important stage of physical design where all the standard cells get placed inside the core boundary. Overall QoR of the design greatly depends on the fact that how well placement is done. You must have noticed that the placement stage takes quite a large runtime. Actually, the tool performs various steps … Read more
Clock tree synthesis is a process of building and optimizing the clock tree in such a way that the clock gets distributed evenly and every sequential element gets the clock within a target global skew limit. To build the clock tree we have to provide certain constraints as input to the APR tool, which commonly … Read more
Most of the EDA tools used in the VLSI Industry are designed for use in UNIX operating system. These tools must require licenses to work which can be purchased from EDA Companies or a company that is authorized for sales and supports. Synopsys tools can be purchased either from www.synopsys.com or from authorized sales and support … Read more
If a simple question comes before you that “What will impact on the delay of a standard cell if temperature varies? ” Are you going to answer straightforward the delay of the cell will increase with temperature OR The delay of the cell will decrease with temperature? If you are going with either of the above … Read more
Code: INTL0Y032021DFT This interview was held for the position of DFT Engineer with 0 years of experience. I personally felt the questions are good and generic which will help the freshers in other domains too. Round-1: 1) Differences between MOSFET and FINFET ?2) Puzzle: A blind man walking in a desert has 2 red pills … Read more
In modern ASIC design use of multi-bit flip flops (MBFF) has increased due to its various promising advantages of MBFF over single-bit flip flop (SBFF). Traditionally we study only a single-bit flip flop in our academics. So it becomes important to understand the design of multi-bit flip-flops, how it works, and what are the advantages/disadvantages … Read more
We have noticed that when a person enters into the ASIC industry, He/She comes across various EDA tools of different EDA companies. It’s natural for experienced professionals that the name of tools/company easily gets remembered, but for the freshers, they often forget the name because it’s new for them. It has also been noticed … Read more
The tapeout is the final stage of the physical design process which definitely gives a big mental relax to the entire team involved in the project. The process of sending a clean layout file in form of gds/oasis to the foundry for fabrication after passing all the checks set by the foundry is termed as … Read more
A physical design engineer’s main focus is to achieve a decent Quality of Result (QoR) and optimized Power Performance and Area (PPA). The start of this journey begins with the Floorplan steps. What will you achieve at the end of PnR is depends on how good your floorplan is. In case of a macro dominating … Read more
In a broader sense, PnR (Place and Route) stage in physical design is basically Placement and Routing of all the instances present in the netlist in a defined core area in such a way that it should meet design rules and timing requirements. But before starting the actual automatic placement of instances by the PnR … Read more