Silvaco Cello™ is the industry’s most versatile, integrated and easy-to-use solution for digital cell library creation and optimization. It enables designers of digital CMOS ICs to custom-tailor digital cell libraries and explore the impact of alternate device models, design rules and cell architectures, as well as process migration.

With Silvaco Cello, designers can control and alter the individual attributes of all digital library cells, making precise adjustments to cell parameters to fulfill the strictest design requirements. 

For example, transistor sizing strategy, fine-grained drive strength variants and row height can be set to control the trade-off between power usage, frequency and area. The user can balance DFM trade-offs between recommended and required rules, thus optimizing layout resolution without an increase in the total cell area.

Silvaco Cello contains the full set of tools needed to create and characterize standard cell libraries. It complements existing design flows and provides all of the views required by the physical synthesis tools.

Key Features and Benefits

  • Intelligent library planner allows fast and easy design space exploration with minimal data entry, this enables users to define and create the optimal library for the application in a minimum of time
  • Fast setup and assimilation of process technologies and foundry design rules, enabling DRC clean layout generation in the first week of use
  • Advanced routing engine, capable of routing standard cells while taking all complex rules and routing restrictions into consideration, maximizing resource utilization in 28nm process node and below
  • Advanced process technology support down to 7nm, including context sensitive spacing and enclosure rules, preferred shape patterns, double-patterning and support of local interconnect
  • Discrete transistor-sizing for FinFET and other non-planar technologies
  • Scalable parallel processing with run times scaling linearly with the number of computing resources
  • Built-in SPICE simulator (SmartSpice™) with optional integration with third-party SPICE simulators and extraction engines
  • Integration with leading third-party DFM, DRC and LVS verification tools to ensure high-quality sign-off layouts and minimal disruption to customer existing flows
  • Generate footprint-compatible cells starting with GDSII or automatically generated layouts to create fine-grained drive and skew variants, enabling late-stage speed and power optimization
  • Advanced Layout Migration Flow
    • Significant productivity improvement
    • Migrates entire cell libraries to different process technologies or cell architectures
    • Uses cell templates to configure predefined shapes, routing parameters, track height, gate pitch, P/N ratios, size and position of power rails, etc.
    • Resizes transistors to satisfy new template or drive strength requirements, also allowing creation of gate length variants required for low leakage applications
    • Supports wide range of layout migration methodologies
  • Scripting interface support provides the flexibility to integrate Silvaco Cello into existing design flows and perform design goal searching through iterative loops

General Features

Fully automated layout topology generation using advanced optimization algorithms that minimize cell area and parasitic effects. Optimization strategies include:

  • Optimal cell input sequencing
  • Optimal diffusion strip layout
  • Transistor netlist synthesis with built-in transistor sizing algorithms and override options including logical effort
  • Adaptive or user-enforced application of recommended rules and wire-spreading for DFM improvement
  • User-definable topology generators with support for an advanced parameterized set of layout primitives:
    • Contact and contact arrays
    • Single and folded transistor configurations
    • Routing preferences and pattern restrictions/allowances
    • Input and output port guidance and blockages
  • Advanced proprietary compaction engine:
    • Layout-to-layout 2-D compaction engine
    • Support technology nodes from 180nm to 14nm
    • Easy interface to describe most common design rules
    • Powerful rule description API in Python enables coding of custom design rules in technologies below 14nm
  • Scalable parallel execution of SPICE simulations and layout generation through:
    • LSF™ from Platform Computing®
    • SUN® Grid Engine (SGE)
    • Multi- and single-threaded processing
  • Built-in verification, including:
    • Formal verification of layout vs. expression
    • Extensive timing and power model validation
    • Interface to external physical verification for independent QA
    • DFM analysis and scoring through external verification tools

Cell Types

  • Buffers (inverting, non-inverting, clock)
  • Boolean combinational (AND, OR, NAND, NOR, AOI, OAI, OA, AO, MUX)
  • Arithmetic (XOR, full-adder, half-adder)
  • Sequential (latches, clock-gates, D-type flip/flops with any optional combination of scan input, set and reset)
  • Miscellaneous (tie cells, filler cells, antenna, diode, ECO gates)
  • User-defined complex gates based on Boolean equations
  • User-defined cells from SPICE netlists



  • Foundry provided transistor models
  • Silvaco Technology Language file containing foundry design rules


  • Liberty (.lib) formatted libraries with CCS, ECSM and NLDM/NLPM data
  • Verilog® and SPICE netlists
  • LEF (Library Exchange Format)
  • GDSII (Graphics Design System II) cell layouts
  • Library databook in HTML and PDF format
  • Cell schematics
  • Open Access database

Platform Support

  • Red Hat Enterprise Linux® version 6 (x86 or x86-64)
XOR2_X1 AOI22_X1
XOR2 cell sample (FreePDK15) AOI22 cell sample (FreePDK15)