What is clock tree synthesis in physical design?
What is clock tree synthesis in physical design?
CLOCK TREE SYNTHESIS (CTS) CTS is the process of connecting the clocks to all clock pin of sequential circuits by using inverters/buffers in order to balance the skew and to minimize the insertion delay. All the clock pins are driven by a single clock source.
Why clock tree synthesis is required?
Clock Tree Synthesis is a process which makes sure that the clock gets distributed evenly to all sequential elements in a design. The goal of CTS is to minimize the skew and latency. Less clock tree inverters and buffers should be used to meet the area and power constraints. …
What is CCD in physical design?
IC Compiler II introduces a new Concurrent Clock and Data (CCD) analysis and optimization engine that is built-in to every flow step resulting in meeting both aggressive performance and minimizing total power footprint.
What are the inputs for CTS in VLSI?
CTS is the process of insertion of buffers or inverters along the clock paths of ASIC design in order to achieve zero/minimum skew or balanced skew. Before CTS, all clock pins are driven by a single clock source. CTS starting point is clock source and CTS ending point is clock pins of sequential cells.
How do we decide transition limits for a design?
Design rule constraints: Transition time is decided on the basis of rise time and fall time. This constraint (max_transition) is based on the library data. For the nonlinear delay model (NLDM), output transition time is a function of input transition and output load.
Why do we use a clock tree?
HFNS are used mostly for reset, scan enable and other static signals having high fan-outs. There is not stringent requirement of balancing & power reduction. Clock tree power is given special attention as it is a constantly switching signal.
What is PrimeTime Synopsys?
PrimeTime is a Static Timing Analysis (STA) tool from Synopsys. This is a simple description to use PrimeTime for VLSI class project. In Project #6, you will learn to find critical path using PrimeTime from your synthesized Verilog code.
What is insertion and transportation delay?
While building the clock tree ,cts starts building the clock from the clock source to the sinks . Once The clock was build and now the clock signal has to travel from the source to the sinks. The amount of time taken by the clock signal to travel from source to sinks is called the insertion delay.
How does CTS reduce insertion delay?
Fixes :
- Vt swapping : Replace LVT/ULVT cells with HVT cells.
- Add buffers in data path to increase data path delay.
- Downsize drivers in data path.
- Layer optimization in data path : Use lower metals with higher RC Values to route in data path.
- Fix cross talk using NDR Rules during routing stage.
Why is CTS needed?
Offering Cheque Truncation System (CTS) is a step in this direction. In addition to operational efficiency, CTS offers several benefits to banks and customers, including human resource rationalisation, cost effectiveness, business process re-engineering, better service, adoption of latest technology, etc.
What is clock trunk?
The “trunk” is the reference clock and the “branches” are the various. output clocks.
What is the goal of clock tree synthesis?
The goal of clock tree synthesis is to get the skew in the design to be close to zero. i.e. every clock sink should get the clock at the same time. Power – Clock is a major power consumer in your design. Clock power consumption depends on switching activity and wire length.
How to synthesize clock trees in VLSI physical design?
What are clock trees? What are clock tree types? How many clocks were there in this project? How will you use to take care of all clocks used in your project? Are they come from seperate external resources or PLL? How will you synthesize clock tree? Why double spacing and multiple vias are used related to clock?
What is the difference between clock tree synthesis and high fanout synthesis?
What are the difference between High Fanout synthesis and Clock tree synthesis? Why CTS not done in synthesis? why we prefer clock buffer during cts, how they are different with normal buffer? what is the target clock skew, clock latency target in your project? Does the design have a PLL? How many clocks generated from PLL.
How is clock tree routing based on equalization?
It is an easy approach that is based on the equalization of wire length. In H tree-based approach the distance from the clock source points to each of the clock sink points are always the same. In H tree approached the tool trying to minimize skew by making interconnection to subunits equal in length.