- Cadabra Design Automation, Inc.
- Cadence 802.11 wireless LAN IP
- Cadence Design Foundry
- Cadence Design Systems
- Cadence PANTA IP cores
- Cadis GmbH
- CADIX Corporation
- CADIX ECAD division
- CadMOS Design Technology, Inc.
- Cadnetix Corporation
- CAE systems
- CAE Technology Inc.
- Caeco Inc.
- Caedent Corporation
- Caetek Inc.
- California Design Automation, Inc.
- Calma Company
- Calypto Design Systems, Inc.
- Carbon Design Systems
- CARDtools Systems
- Carnegie Mellon University
- Cascade Semiconductor Solutions, Inc.
- CAST, Inc.
- Catalytic Inc.
- Catapult C Product Division
- CEA
- CEA-Leti
- Celestry Design Technologies Inc.
- Celoxica Holding Plc.
- Certess Inc.
- Certus Semiconductor
- CEVA
- CheckLogic Systems inc.
- Chip & Chip, Inc.
- Chip Estimate Corp
- Chip Path Design Systems
- CHIPit business unit
- ChipStart LLC
- Chronologic Simulation
- Chronology Inc.
- Chrysalis Symbolic Design, Inc.
- CIDA Technology, Inc.
- CIM-Team GmbH
- CiraNova Inc.
- Clear Shape Technologies
- Cliosoft, Inc.
- CLK Computer-Aided Design, Inc.
- CLK Design Automation, Inc.
- Co-Design Automation, Inc.
- Codasip Ltd.
