ASIC Design Flow

1. K.YOGESHWARAN
ASSISTANT PROFESSOR/ECE
KIT-KALAIGNARKARUNANIDHI INSTITUTE OF
TECHNOLOGY,CIOMBATORE
emperoryogi.yogesh@gmail.com
9789631474
ASIC DESGIN FLOW

2. Design Flow

3. LOGICAL DESIGN(FRONTEND) Consists of following steps
1.Design Entry
2.Logic Synthesis
3.System Partitioning
4.Pre Layout Simulation
PHYSICAL DESIGN(BACKEND) Consists of following steps
1.Floorplanning
2.Placement
3.Routing
4.Circuit Extraction
5.Post Layout Simulation

4. 1. Design entry - Using a hardware description language ( HDL ) or
schematic entry
2. Logic synthesis - Produces a netlist - logic cells and their
connections
3. System partitioning - Divide a large system into ASIC-sized pieces
4. Prelayout simulation - Check to see if the design functions
correctly
5. Floorplanning - Arrange the blocks of the netlist on the chip
6. Placement - Decide the locations of cells in a block
7. Routing - Make the connections between cells and blocks
8. Extraction - Determine the resistance and capacitance of the
interconnect
9. Postlayout simulation - Check to see the design still works with
the added loads of the interconnect

5. 1.Design Entry
 The designer starts the design with a text description
or system specific language like HDL, C language etc.
2.Logic Synthesis
Logic synthesis is the process of converting a high-
level description of design into an optimized gate-level
representation.
It generally helps to produce the netlist consisting the
description and interconnection of logic cells.

6. 3.System Partitioning
 Goal: Partition of a System into number of ASIC’s
 Objective: Minimize the number of external
connection between each ASIC. Keep each ASIC
smaller than max size.

7. Partitioning of a large design into a small
ASIC design takes place.
This is done mainly to separate different
functional blocks and also to make
placement and routing easier.

8. 4.Pre Layout Simulation
Prelayout Simulation allows checking whether
the design functions correct or not.
Gate level functionality and timing(Delay)
details can be verified.
It is also called as Functional Verification.

9. 5.Floorplanning
Goal: Calculate the size of blocks and assign
them locations.
Objective: Keep highly connected blocks
physically close to each other.
It is the first step in the physical design flow.
Arrange the blocks of the netlist on the chip.
It is the Tentative placement of its major
functional blocks.

10. Slicing Floorplan:
One that can be obtained by
repetitively subdividing (slicing)
rectangles horizontally or vertically.
Non-Slicing Floorplan:
One that may not be obtained by
repetitively subdividing alone.

11. 6.Placement
Goal: Assign the interconnect areas and the
locations of all the logic cells with in the flexible
block.
Objective: Minimize the ASIC area and the
interconnects.
Allows the placement of cells present in the
block.
Assigns exact locations for various circuit
components within the chip’s core area.
Placement is much more suited to automation
than Floorplanning.

13. 7.Routing
 Make the connections between cells and blocks.
 It is the process of creating physical connections
based on logical connectivity. signal pins are
connected by routing metal interconnects.
Global Routing:
 Goal: Determine the location of all the interconnects.
Objective: Minimize the total interconnect area.
 Wire segments are tentatively assigned (embedded)
within the chip layout .

14. Detailed Routing:
 Goal: Completely route all the interconnects on the
chip.
 Objective: Minimize the total interconnect length
used.
 Find actual geometric layout of each net within
assigned routing regions.

15. 8.Circuit Extraction
 Determine the resistance and capacitance of the
interconnect.
 Basically it’s link between two domains.
1.Physical Domain
2.Electrical Domain
 Physical domain -it’s uses the physical information
like shapes of the design.
 Electrical domain-provide the electrical information's
(connectivity of C,R,L)

16. 9.Postlayout simulation
Post-layout simulation you can extract the
parasitic interconnect.
To verify that your functional stimulus still
works with accurate timing.

17. THANK YOU