Clock tree synthesis pdf file

Single clock normal synthesis and optimization multiple clocks synthesis each clock seperately multiple clocks with domain crossing synthesis each clock seperately and balance the skew how many clocks were there in this project. I just used to give the clock buffer and clock inverter foot prints for the purpose. An input to the design rule tool is a design rule file. Dont touch circuits and pins in front end logic synthesis are treated as ignore circuits or pins at back end physical synthesis. The original clock root is partitioned into several pseudo clock sources at the gate level. Ic compiler ii is specifically architected to address aggressive performance, power, area ppa, and timetomarket pressures of.

Innovus implementation system clock concurrent optimization with true multithreading the innovus implementation system features a nextgeneration clock concurrent optimization engine with true multithreading, enhanced useful skew, and flow integration. Its often the case that a single reference clock will be cascaded and. Form design design import complete the design tab as shown figure 1. The complexity of the clock tree and the number of clocking components used depends on the hardware design. Pdf an efficient clock tree synthesis method in physical. With these series of lectures, we have explored onsite concepts applied in vlsi industry. Telehealth appointments in a secure, hipaacompliant platform. In the generate clock spec window, select bufx2 through invx8 and then click add so that they appear in the selected cells list, as shown.

I need to know what all things should be taken care in the clock tree sppecification file for an optimized clock tree. You must enter the file names with wild card character and use the file widget to browse and select the other file names. Minimizing clock latency range in robust clock tree synthesis wenhao liu yihlang li huichi chen you have to enlarge your font. Clock tree synthesis cts plays an important role in building wellbalanced clock tree, fixing timing violations and reducing the extra unnecessary pessimism in the design. Lecture 8 clock distribution techniques stanford university. The registers near the clock port face large insertion delays. Are they come from seperate external resources or pll. This paper aims to share practical experience regarding building a poweroptimized clock tree, determining the optimum targets for clock tree synthesis cts and monitoring the quality of results qor along the way. Basic terminology in physical design vlsi basics and.

The engine merges physical optimization with clock tree synthesis cts, simultaneously building. Whats the difference between cts, multisource cts, and. Synopsysic compilertutorial foralogicblock using theuniversityofutahstandard celllibraries inonsemiconductor 0. Cluster clock nodes and build a local tree by the load balance based cts methods create a buffered rc network from the local clock tree minimize clock skew by wire sizing and snake routing zadvantages. Tutorial for encounter washington university in st. Anyfrequency clock synthesis format translation integrated input mux integrated vcxo vdd level translation glitchless switching between clocks at different frequencies integrated loop filter clock division hitless switching synchronous output clock disable holdover integrated power supply filtering features that simplify clock tree design. By converting load enable circuits to clock gating circuit dynamic power can be reduced. How will you use to take care of all clocks used in your project. Cts is the process of inserting buffersinverters along the clock paths of the design in order to balance the skew and to minimize insertion delay. Implications on timing lets remember our famous timing constraints. At the end of this section, we introduce the clock.

Clock tree synthesis cts is one of the most important stages in pnr. Pdf clock power dissipation has become a significant issue since it occupies around half of the total system power. Clock tree synthesis is a process which makes sure that the clock gets distributed evenly to all sequential elements in a design. Clock tree networks are pillars and columns of a chip. Synopsysiccompilertutorial foralogicblockusing the. General usage, clock tree synthesis, placement, route, extract rc, timing analysis, and inplace optimization. General usage, clock tree synthesis, placement, route.

It is specific to your project more the clocks more challenging. Cts is the process of insertion of buffers or inverters along the clock paths of asic design in order to achieve zerominimum skew or balanced skew. Is it possible to do this in the clock tree specification file. Click mode, then select cts, in cts select the optimization tab, select resize and insert bufferinverter, then click ok. Clocktree is easy and your clients will love the convenience. Questions related to clock tree synthesis what is the goal of cts. In most of the ics clock consumes 3040 % of total power. Sdc synopsys design constraints the rules that are written are referred to as constraints and are essential to meet designs goal in terms of area, timing and power to obtain the best possible implementation of a circuit. Since systems can have several ics with different clock performance requirements and frequencies, a clock tree refers to the various clocks feeding those ics. Clock tree synthesis and soc clock distribution strategies. The formal definition of whitespaceaware tsv arrangement problem in 3d clock tree synthesis is as follows.

Furthermore, the book contains indepth discussions on the basis of synopsys technology libraries and hdl coding styles, targeted towards optimal synthesis. To begin this lab, get the project files by typing the following command. I think the position of page topic is too low such that the content space is limited. Pdf an efficient clock tree synthesis method in physical design. But when enable becomes one in between positive level of the clock a glitch is obtained. The goal during building a clock tree is to reduce the skew, maintain symmetrical clock tree structure and to cover all the registers in the design. Ic compiler ii is specifically architected to address aggressive performance, power, area ppa, and timetomarket pressures of leadingedge designs. Questions related to clock tree synthesis vlsijunction. The experiments that will be presented were conducted on a. The clock tree structure will be htree similar to the figure1.

An efficient clock tree synthesis method in physical design. In addition, crucial issues related to layout, which includes clock tree synthesis and backend integration links to layout are also discussed at length. We will discuss about skew and insertion delay in upcoming posts. Apart from these, useful skew is also added in the design by means of. Addressing clock tree synthesis cts challenges in soc. Dft timing design methodology for atspeed bist yasuo sato1.

Clock tree synthesis cts up until this point, the clock tree has been treated as idealthe clock arrives to every ipop at exactly the same time. If physical location wasnt a problem, clock tree synthesis would only. It is a onestopshop to understand industrial vlsi circuits. Whitespaceaware tsv arrangement in 3d clock tree synthesis. The goal of cts is to minimize the skew and latency. Introduction to multisource clock tree systems a renewed emphasis on highfrequency clock design has heightened interest in multisource clock tree synthesis cts. So in order to balance the skew and minimize insertion delay cts is performed. Whats the difference between cts, multisource cts, and clock mesh. This effect is due to the clock balancing nature of automated cts engine. Combines grid and binary tree put global distribution into spine makes it more regular local distribution is still custom global local regular custom global dist. Minimizing clock latency range in robust clock tree synthesis. Definition clock tree synthesis cts is a process which make sure that the clock gets distributed evenly to. Multisource clock tree synthesis is a relatively new option for clock distribution, joining conventional clock tree synthesis.

It also includes the files necessary to run signal integrity and power estimation using synopsys primetimesi, primetimepx and mentor graphics questa. With automatic clock tree synthesis, the cts engine puts a lot of buffers across the chip that are not desired. Stinson ee 371 lecture 1 2 clock distribution metrics. Clock distribution and balancing methodology for large and. Clock distribution 3 clock tree synthesis 4 additional subjects. There are two types of stop pins known as ignore pins and sync pins. For this tutorial we will generate layout for the gatelevel netlist of the greatest common divisor gcd circuit synthesized in tutorial 2. Timing optimization prects cadedi flow synthesize clock tree. Clock tree synthesis clock tree synthesis cts is the process of inserting buffersinverters along the clock paths of the asic design to balance the clock delay to all clock inputs. But clock switches continuously, increasing the dynamic power consumption. Skew is the difference in arrival of clock at two consecutive pins of a sequential element. This paper proposes a method aiding in low clock skew applicable to the mainstream industry clock tree synthesis cts design flow. Once the netlist has successfully been placed and routed, you should be. During clock tree synthesis, the dont buffer nets exception has priority over the clock tree design rule constraints.