As an example, consider a very simple circuit comprising an or gate driving both a buf buffer gate and a. Full gatelevel simulation gls is an obvious choice to get the act ivity at each gate level node. The gate macros and python code written for this project will serve as a template for the rdg to. Use the simulation library compiler or nativelink to compile simulation models. Aug 03, 2016 i have been working in gls fullypartly since 2 years in one of the soc company. Treat xgobblers as sketchy engineers like to put xgobblers on their gate simulation models like rams, fuses, and plls because the ram model authors love to drive xs out of their ram. At this point, the gatelevel simulation is pretty similar to asic stuff. Design architect is a leading cadeda tool from mentor graphics. This is because the delay of req makes the value change from 0 to 1 happen after the rising edge of clkb. If gls gate level simulation is running after place and route then one has to annotate sdf standard delay format file. To run simulation, use one of the following methods. Methods of instrumenting synthesizable source code to enable debugging support akin to highlevel language programming environments for gatelevel simulation are provided.
Performing gatelevel simulation gives us the opportunity to check that our circuit still works properly after being synthesized and placed and routed. Us6240376b1 method and apparatus for gatelevel simulation. It is a significant step in the verification process. In the category list, select simulation under eda tool settings. Simulation can be performed at varying degrees of physical abstraction, such as at the transistor level, gate level, registertransfer level rtl, electronic systemlevel esl, or behavioral level. This is ok in rtl simulation, but with gls it causes everything to go x. Remove x propagation in gate level simulation abstract. Additionally, we use the gate level simulations to obtain switching activies for each gate in the design. In the processing menu, point to start and click on start eda netlist writer. Logic simulation is currently one of the main verification tools in the design or verification engineers arsenal. However, full gls runs are notoriously difficult to get running correctly, and this approach was not considered viable for the large number of tests we hope to run.
One fix is your design team could place an assertion on every dff in their design, but that would be a huge maintenance. It can be used to simulate gate level and transistor level circuits. Method and apparatus for gate level simulation of synthesized register transfer level designs with source level debugging. Zerodelay gatelevel simulations netlist simulations with no sdf or delays typically account for 90% of all the gatelevel simulations run by verification engineers. Creating gate level schematics and simulation design architect and eldo. X propagation in gls is mostly caused by x pessimism, so it is practical to suppress them and focus on the main purpose of gls. Introduction this document describes how to perform gatelevel design and simulation of logic circuits using cadence virtuoso with the ncsu design kit. Now i am trying to simulate the same using the same verification env. This technique is orders of magnitude faster than traditional gatelevel simulation. Performing gate level simulation gives us the opportunity to check that our circuit still works properly after being synthesized and placed and routed. Tutorial for gate level simulation verification academy. Gatelevel simulation with gpu computing debapriya chatterjee university of michigan andrew deorio university of michigan and valeria bertacco university of michigan functional veri.
Formalpro gatelevel regression testing of asics mentor. Design flows overview ug892 ref 9 simulation flow simulation can be applied at several points in the design flow. In this case, flipflop sync1 in gate level simulation cannot sample value 1 on req, which can be sampled in the corresponding cycle in rtl simulation. What are various things i need to keep an eye on in debugging this. Full gate level simulation gls is an obvious choice to get the act ivity at each gate level node. Logic simulation is the use of simulation software to predict the behavior of digital circuits and hardware description languages.
The increase in design sizes and the complexity of timing checks at 40nm technology nodes and below is responsible for longer run times, high memory requirements, and the need for a growing set of gate level simulation gls applications including design for test. In the tool name list, specify simulation tool as modelsimaltera. Through this project, gate was determined a suitable tool for the rdg to employ in their research and design of future detector systems. It means a test which takes x ns in rtl simulation will take the same amount in gate level simulations too. The design netlist output file is a netlist of the design mapped to architecturespecific primitives. Automatic water level indicator and controller can provide a solution to this pro blem. Designs that take days or even weeks to simulate with gatelevel simulation can be verified in hours or even minutes using formalpro. Do not turn on run gate level simulation automatically. Gate level simulation is increasing trend tech trends. Gatelevel simulation with modelsimaltera simulatorverilog hdl. In this tutorial you will create a schematic for a basic digital logic gate, and and gate, and perform some basic simulations on the schematic to verify it is functioning properly.
For gatelevel simulation, the eda netlist writer generates a synthesized design netlist verilog output file. The stratix ii device atom libraries required for gatelevel simulation are also provided with the example. Mixed hdl if your design is a mix of vhdl, verilog hdl, and systemverilog files, you must use a mixed language simulator. Including the entire contents of other verilog source file. Compile time switches that are usually used in gatesim. Tutorial using modelsim for simulation, for beginners. If there are no errors in your design, modelsim will open. The term gate level refers to the netlist view of a circuit, usually produced by logic synthesis. In essence, logic analysis may be viewed as a simplification of timing. Gate level simulation overcomes the limitations of statictiming analysis and is increasing being. Method and apparatus for gate level simulation of synthesized register transfer level design with source level debugging us09127,584 us6240376b1 en 19980724. It is the authors hope that after reading this tutorial the reader will be able to independently implement their own simple design such as lab 1. The increase in design sizes and the complexity of timing checks at 40nm technology nodes and below is responsible for longer run times, high memory requirements, and the need for a. Simulation can be performed at varying degrees of physical abstraction, such as at the transistor level, gate level, registertransfer level rtl, electronic system level esl, or behavioral level.
Institute of physics publishing physics in medicine and biology phys. The gatelevel design is generated after par is done which gives you a netlist of the design as it will exist on the fpga and a timing annotation file sdf format the same as you get in the asic world. When the complexity of an integrated circuit design reaches the point where electrical analysis is no longer costeffective, logic simulation or gate level simulation may be used. I am getting some fails rit at the beginning of my simulation. What are the benefits of doing gate level simulations in vlsi. It is one of the first steps after design entry and one of the last steps after implementation as part of the verifying the. Rather than dealing with voltages and currents at signal nodes, discrete logic states are used. In order to run your simulation, you need to create a project. Gate level simulation is used to boost the confidence regarding implementation of a design and can help verify dynamic circuit behaviour, which cannot be verified accurately by static methods. You may also need to compile models from the altera simulation libraries. Setting up simulation with analog design environment ade running functional simulations transient analysis appendix a. A file containing a list of all the first flops of the synchronizes in the design where a timing violation is guaranteed and thus taken cared of by the design such as placing synchronizers. We do not want to wait until all the ip blocks or even the standard delay format sdf file are ready. This is a silent chipkiller if it happens in your rtl simulation.
For ece331, we will only perform schematic design and simulation of logic gates. Additionally, we use the gatelevel simulations to obtain switching activies for each gate in the design. The most common form of logic simulation is known as event driven because, perhaps not surprisingly, these tools see the world as a series of discrete events. The most difficult part in gate level simulation gls is x propagation debug. One method of facilitating gate level simulation includes generating crossreference instrumentation data including instrumentation logic indicative of an execution status of at least one synthesizable. Need to add paths to simulation setup for gate level simulation.
Using the vivado ide ug893 ref 2 vivado design suite user guide. As of my knowledge every soc company is depending on gls, even after efficiently using rtl simulations, advancements in static verification tools like sta static tim. In gls, these force statements can be put into a file, and included in simulation. I have been working in gls fullypartly since 2 years in one of the soc company. For item 3, a complete synchronizer list should be created, and the first stage flop instances have timing check disabled. Gatelevel simulation with gpu computing article pdf available in acm transactions on design automation of electronic systems 163. The typical rtl to gatelevel netlist flow is shown in the following illustration. In this tutorial, we will be using design architect to implement a nor gate shown below, and simulate it using. The only 100% sure way to catch this is through gls sdf runs. For designs greater than 100,000 gates, formalpro is an essential verification tool in an asic design flow. A test bench can be simple in structure and can sequentially apply. Nov 27, 2011 please note although, gate level simulations take a lot of real time compare to rtl simulation, the time intervals in the test is the same.
In my experience, my testbench is running good on rtl simulations but on gate level simulations some problems suddenly appear like my assertions are failing because of glitches, sampling of data by the monitor is wrong, etc. Gatelevel simulation methodology improving gatelevel simulation performance author. The operation of water level controller works upon the fact that water conducts electricity due to the p. You can also set up the test bench to display the simulation output to a file, a waveform, or to a display screen. All functional libraries and device atom libraries come with the quartus ii software. What are the benefits of doing gate level simulations in. Start a new quartus project using the project wizard and choose sums as the name of design and top module. Unisim gatelevel model for the vivado logic analyzer secureip library. There are different ways to annotate sdf file in simulation, one should confirmed in simulation for a successful annotation by looking in. Go to the tools menu, under eda simulation tool, click run eda gate level simulation. Improving gatelevel simulation performance with incisive enterprise simulator 2. Oct 05, 2018 we need to start gatelevel simulation earlier in the verification cycle. Verify correctness of synthesized circuit verify synthesis tool delaytiming estimates synthesis tool generates. Mar 03, 2014 if gls gate level simulation is running after place and route then one has to annotate sdf standard delay format file.
What i need are the proper way on creating a testbench for a gate level simulation. To create a pdf of your schematic select, file print, and then print to file pdf. You can also select the directory path in this window. Gate level simulation methodology improving gate level simulation performance author. When the complexity of an integrated circuit design reaches the point where electrical analysis is no longer costeffective, logic simulation or gatelevel simulation may be used. Direct stimulus to use gate level verilog, not behavioral. Gatelevel simulation with modelsimaltera simulator. So in any case, we wrote this script to do the synthesis. Designs that take days or even weeks to simulate with gate level simulation can be verified in hours or even minutes using formalpro. Therefore we dont check timing violations in this path. Improving gate level simulation performance author. Gatelevel timing simulation placeandroute in the quartus ii software produces a design netlist. Page 19 quartus tutorial with basic graphical gate entry and simulation last verified for quartus prime lite edition 18.
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