Vlsi Design Styles in Digital Design

Digital Design can be implemented by various design styles. And depending on the market requirement different design styles are used.

• Programmable Logic Design
  • Field Programmable Gate Array (FPGA)
  • Gate Array
• Standard Cell (semi custom design)
• Full Custom Design

• Field Programmable Gate Array (FPGA):
  • Using VHDL or verilog
  • Implementation
    • Placement and Routing
    • BitStream Generation
    • Analyse timing, view layout, simulations etc
• Gate Array: Gate Array design implementation is done with metal design and processing. The implementation requires two-step manufacturing process
  • First phase, which is based on standard masks, results in an array of uncommitted transistors on each GA chips
  • These uncommitted chips can be customized later, which is completed by defining the metal interconnects between the transistor of the array
  • In this chip utilization factor is higher than that of FPGA
  • Chip speed is higher
• Standard Cell or Semi Custom Design:
  • The standard-cells based design is often called semi custom design.
  • The cells are pre-designed for general use and the same cells are utilized in many different chip designs. 
• Full Custom Design
• Full custom design involves creating IC where each individual transistors architecture and interconnections are specified. Designers manually place transistors, resistors,capacitors and other components at the transistor level