What is CTS algorithm?
CTS (Clock Tree Synthesis) process is carried out after placement of macros and standard cells, because only after placement of cells the exact physical location of cells can be identified which is needed to establish the tree structure in the design.
What is clock tree optimization?
It primarily focuses on timing, power and area optimization by applying different optimization techniques at each stage of the design. Clock Tree Synthesis (CTS) is an important step in physical design flow. CTS builds the clock tree by balancing the skew in the entire design for all the clocks present.
What is CCD in VLSI?
A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a major technology used in digital imaging.
What is clock trunk?
The “trunk” is the reference clock and the “branches” are the various. output clocks. Example “Clock Tree”
Why clock tree synthesis is required?
The purpose of Clock Tree Synthesis is to reduce skew and delay. Clock Tree Synthesis is provided the placement data as well as the clock tree limitations as input.
What is synthesis in VLSI?
Synthesis in VLSI is the process of converting your code (program) into a circuit. In terms of logic gates, synthesis is the process of translating an abstract design into a properly implemented chip.
What are clock tree exceptions in VLSI?
An exclude pin is a clock sink whose timing is not important. Excluding a pin from the clock tree removes individual default clock sinks or branches of a clock tree. Clock tree synthesis does not calculate skew and insertion delay for the excluded clock sinks or branches.
What is a clock buffer used for?
Clock buffer is typically used to fan out clock signal and isolate the source from the loads. by default buffer doesn’t have PLL inside, rather some input and output stage.
What is DEF file in VLSI?
DEF file is used to represent the Physical layout of an Integrated Circuit (IC) in ASCII format. A DEF file is strongly connected with the Library Exchange Format (LEF) file. So both files are needed for a correct display of physical design. DEF file format was developed by Cadence Design System.
Which is are the types of the clock tree?
A clock tree can have different structures such as:
- Fish bone.
- H-tree.
- X-tree.
- Multi-level clock tree.
- Once the Clock Tree Synthesis is complete, we must double-check the timing.
Why buffers are used in clock tree?
A buffer tree is built to balance the loads and minimize skew, there are levels of buffer in the clock tree between the clock source and clock sinks.
What is CCD and CMOS?
CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor) image sensors are two different technologies for capturing images digitally. Each has unique strengths and weaknesses giving advantages in different applications.
What is CCD made of?
The CCD itself is primarily made of silicon and the structure has been altered so that some of the silicon atoms have been replaced with impurity atoms. The figure below shows a very simplified cross section through a CCD. It can be seen that the Silicon itself is not arranged to form individual pixels.
Why do we use buffers in a clock tree?
The clock buffers are designed with some special property like high drive strength, equal rise and fall time, less delay and less delay variation with PVT and OCV. Clock buffer has an equal rise and fall time. This prevents the duty cycle of clock signal from changing when it passes through a chain of clock buffers.
What is clock tree synthesis (CTS)?
Clock Tree Synthesis (CTS) is one of the most important stages in PnR. CTS QoR decides timing convergence & power. In most of the ICs clock consumes 30-40 % of total power. So efficient clock architecture, clock gating & clock tree implementation helps to reduce power. The process of distributing the clock and balancing the load is called CTS.
What is the difference between hfns and clock tree synthesis?
Difference between High Fanout Net Synthesis (HFNS) & clock tree Synthesis. Buffers and clock inverter with equal rise and fall times are used. whereas HFNS uses buffers and inverters with a relaxed rise and fall times.
What is clock-mesh architecture?
In the clock-mesh architecture, the root clock signal is split into parallel path using a tree of drivers that then feed an array of buffers that are cross connected in a metal mesh from which paths down to the clock sinks are routed.
What is clock routing algorithm?
This is another binary tree-based routing algorithm in which clock routing is achieved by constructing a binary tree using exclusive geometry matching. Unlike the Method of mean & median (MMM) algorithm which is top-down and this is bottom-up fashion.