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SILVACO, Inc., a Delaware corporation headquartered in Santa Clara, California, is the leading supplier of Technology Computer Aided Design (TCAD) software, and a major supplier of Electronic Design Automation (EDA) software for circuit simulation and design of analog, mixed-signal and RF integrated circuits.

What we Offer ?Silvaco delivers & supports TCAD & Integrated EDA software products in following segments. 1) TCAD - Complete family of 2D and 3D process, device and stress simulation products. 2) Analog/Mixed-Signal/RF - Complete family of full-chip and circuit simulation products for analog, mixed-signal, and RF. 3)Custom IC CAD - PDK-based design flow with schematic, layout, physical verification, and parasitic extraction. 4)Digital CAD - Cell/core library characterization, place and route, and Verilog simulation products.

Introduction to Silvaco EDASilvaco provides Integrated Flow(Single vendor), tools which work together, easy to install, easy to maintain, easy to operate. Silvaco provides Front-end PDK for Schematic driven circuit simulator environment with accuracy, performance to provide complete analog/mixed-signal/RF design flow. Silvaco provides BACK-end PDK for Fast layout Editing with Integrated DRC/LVS, PCell Scripting. All data is present in Silvaco's Foundry PDK which is important for Foundry Interface. Silvaco has developed 5 set of Demo Process design kits 1)Analogue Demo PDK 2)Logic Demo PDK 3)Mixed-Signal Demo PDK 4)Radio Frequency Demo PDK 5)MOSIS SCMOS PDK These PDKs enable educational institutions, design Service providers & fabless companies to be immediately productive in using Silvaco's Integrated IC design capture, Simulation, Layout & verification tools on Linux, Solaris & Windows platform. In this article we will demonstrate how to design & Implement a CMOS Inverter.

Circuit Schematic Capture with GatewaySchematic Editor & Simulator Front End Requirements What circuit designers need? Edit/View Schematics in a user-friendly environment. Create netlists for simulators and layout-vs-schematic tools Manage files for multiple designers and projects

Gate Schematic capture & Editor GATEWAY is a schematic capture tool and is the entry point for the IC design flow.Gateway is the entry point of the design as its main purpose is generating a netlist that can be loaded into circuit simulators. Gate way Schematic editor is Powerful frontend schematic editor & viewer. Integrated with Smartspice & Smartview. Creates multi-sheet, multi-view, hierarchical, Flat Designs. Generate both schematic netlist & LVS netlist from the same schematic. Hierarchical DC bias for all currents & voltages. Gateway supports importing/exporting of EDIF(Electronic design Interface Format) version 2 0 0 files. Ability to switch processes & run process variant simulation on same schematic.

Gateway features easy & flexible way of library management. Create a Workspace, Click on File-->New-->Workspace . After Saving your Workspace we need to add the library which is necessary for our simulation. The image below for this Demo shows the Necessary Library file that has to be added.

The following necessary library will be added, all those symbol libraries will appear which we will be using in our CMOS inverter design which is shown in Symbol/Options dock window as shown in above fig. Next we create a new schematic for our CMOS Inverter design Click on File--->New--->Schematic

Save the Schematic as CMOS Inverter

The above image shows you the schematic of CMOS Inverter Circuit. Gateway offers 3-level circuit check functions(check this level. check this level & below, Check all levels) if there is any errors/warnings designers can easily locate them by double clicking the error/warning message in the Output/Probe/Errors dock window Once the Check all level verification is completed simulation of CMOS inverter is done by SmartSpice which is Integrated with Gateway.

What is this SmartSpice?SMARTSPICE is a high quality, commercial grade, general purpose circuit simulation program for nonlinear DC, nonlinear transient, and linear AC analyses.SmartSpice easily fits in to your analog design flow, supports foundry supplied device models. SmartSpice is 100% HSPICE compatible for netlists, models, analysis features & result.

What are the features of SmartSpice?Model & Simulation Accuracy.Advanced stepping algorithm & automatically adapt to circuit topology. Handles 1st, 2nd, 3rd derivatives. Berkeley style of model interface.

Support of standard compact models.Berkeley SPICE model compatibility include following models BJT/HBT: Gummel-Poon, Quasi-RC, VBIC, MEXTRAM, MODELLA, HiCUM MOSFET: LEVEL 1, LEVEL 2, LEVEL 3, BSIM1, BSIM3, BSIM4, MOS 11, MOS 20, EKV, HiSIM, PSP, HVMOS, LDMOS TFT: Amorphous and Polysilicon TFT models: Berkeley, Leroux, RPI SOI: Berkeley BSIM3SOI PD/DD/FD, UFS, LETISOI MESFET: Stats, Curtice I & II, TriQuint JFET: LEVEL 1, LEVEL 2 Diode: Berkeley, Fowler-Nordheim, Philips JUNCAP/Level 500 FRAM: Ramtron FCAP

Support of Verilog-A language for behavioural description. Speed, Convergence, Capacity.2 to 5 times faster than any other SPICE simulator. Multiple-thread functionality for multiple CPU cores. Three direct & 2 iterative solvers designed for optimal simulation performance of circuit topologies. SmartSpice-64 offers capability limited based on the available memory. Multi-million transistor circuits are easily simulated

Circuit debugging. Gateway can generate 2 types of netlists SmartSpice Netlist for circuit simulation. Guardian Netlist for LVS Verification. Clicking on Simulation->Edit control File an SEdit window will pop out in which designers can specify analysis statement, options, parameters, the necessary model files are included

We can create a symbol for CMOS Inverter circuit which is easy for Post-layout simulation.

Click on tools & then click on Generate Symbol The above image shows the representation of the Schematic Inverter in Symbol for which is used for other simulation purpose which will be discussed later. Next we need to analyse the DC, AC & Transient characteristics of CMOS Inverter. Create a new schematic file & save it as Inverter_trans.schr

You can see the CMOS Inverter design for transient response After this the simulation is ready to be launched. The waveform of simulation is shown in fig below

Layout and VerificationOnce the circuit schematic is working, we can proceed to the layout design and its verification. Like in Gateway and Smartspice, the demo PDK has provided necessary files and settings for layout design and verification. Designers may go through the documentations which are shipped in the PDK package for more details. Layout generation is done through expert.

What is Expert?Expert Layout Editor enables mask designers to achieve maximum density and performance in analog and digital layouts. Experts high-productivity design environment offers fast layout viewing, full editing features, large capacity, and powerful scripting for automation with parameterized cells. In our CMOS Inverter Design Start expert tool. Click on File->New Save the project as CMOSInverter.eld Select the technology file as SCMOS.tcn Load the Pcell Library scoms_subm_pcells to facilitate the design. The Pell library contains those frequently used cells such as MOS, BJT, N-well/Substrate Connection etc. Chose the corresponding Guardian DRC rule file "mosis-cmos-drc.dsf" Configure the Guardian LPE(Hipex) extraction technology to use LISA script file. "inverter_c.cmd" & "inverter_r.cmd"

Figure above shows you the CMOS inverter layout. After finishing the layout design, we can proceed to do the DRC check whether there is violation of design rules. Open DRC script panel load "mosis-cmos-drc.dsf" & run the check Expert-->Verification-->DRC-->DRC run setup-->Enable Command progress bar and Script progress bar. Once the layout becomes DRC error free, we can extract netlist from layout so that we can use it compare with the schematic netlist generated from Gateway. Click Verification-->Extraction-->Setup-->Technology as shown below

After this extraction is invoked from Verification-->Extraction-->Hipex-Net-->Run the netlist extracted from the layout can be viewed from Verification-->Extraction-->Hipex-Net-->View netlist Previously we mentioned that Gateway can generate two netlist formats: Smartspice and Guardian; for LVS we will use the Guardian netlist. By now we have both netlists ready: netlist extracted from layout and the netlist generated from schematic. Invoke Guardian LVS from Expert-->Verification-->Launch LVS. In the following Project Setting dialogue, browse & select netlist from schematic & layout respectively Click OK when the input files have been selected. Click Run LVS button to start LVS. From the LVS log file it can be seen that this layout successfully passed the LVS verification.

So the Netlist matches & the LVS verification is successfully completed.

Extraction & Post layout verificationSince the LVS verification has been passed, normally we assume that the performance of the layout design should be quite close to what we expect from the schematic design. We can do a simulation with the netlist from layout extraction (Hipex-Net), i.e. the netlist that we used just now for LVS. Also, we may consider the parasitics effect of the layout. For example if we want to see the impact of parasitics capacitance, we can run a Hipex-C extraction from Expert-> Verification -> Extraction -> Hipex-C-> Run. After the extraction process finishes, we can view the extracted netlist with parasitic capacitance included It can be opened from Expe