Reviewing ICs

Integrated Circuits:
  • An Integrated Circuit is a device with a large number of electronic circuits built into a plate of Semiconductor material, usually silicon.
  • An SoC is an IC with all components of a complete electronic system built into a single silicon plate (multiple ICs integrated together).
  • It can be built up to several billion transistors in an area of the size of a fingerprint.
  • Categories: Divided into Digital and Analog ICs, operating at a different voltage level.

Digital Circuits:
  • Data will be converted to numbers and to binary numbers and processed as binary.
  • Switches are the basic building blocks of any digital circuit.
  • Types: 
    • Sequential - with memory
    • Combinational - without memory
  • Building Blocks: 
    • Logic Gates
    • Flip Flops - the memory cells
  • Logic Gates: AND, OR, NOT, XOR, NAND, NOR, XNOR
  • Flip Flops - Built with logic gates.
  • All logic gates can be represented using transistors.
FIG: NAND and NOR gates representation by using CMOS transistors.
  • Gates and Flops are formed by transistors, only transistors.
    • CMOS transistors (PMOS and NMOS)
  • Any digital IC consists of a large number of Gates and Flip Flops (millions or billions of transistors).

Hardware Description Language (HDL)
  • Digital IC in the 1960s to 2020 - a few hundreds of transistors to billions.
  • HDL describes the fabrication mask in the semiconductor ICs.
  • Verilog and VHDL.

  • Developed by a company called Gateway design in 1984 acquired by Cadence Design Systems.
  • Verilog = Verification Logic
  • IEEE 1364 Standard in 1995
  • Maintained by NPO called Accellera.

System Verilog
  • An extension of Verilog developed as a new standard.
  • IEEE standard (1800-2005) in 2005.
  • Compared to Verilog, SV added a lot of features to enhance verification capabilities and support functional verification of the IC.
  • Supports Object Oriented Programming (OOPs) for verification.
  • Design perspective, both Verilog and SystemVerilog are the same except for some enhanced design features in SV - Most preferred HDL in the industry.
  • SV is used for testbench creation and verification purposes mostly.

IC Design and Manufacturing Process

FIG: IC Design Process (Source: SystemverilogAcademy)

IC Design Process: Front-end
  • The first step is to describe the functionality of an IC and its microarchitecture is defined.

  • Front End: Digital/RTL Design & Verification
    • Unit level
    • Block/Cluster level
    • System-level/SOC level

IC Design Process: Back-end
  • Once the verified RTL is ready, the code will be converted to digital circuits with only flip-flops and logic gates. This process is called synthesis, and it is done by using EDA tools.
  • The output of the synthesis will consist of list of logic gates connected appropriately to perform the design functionality of the IC, called a netlist - can be assumed as the circuit diagram of the final IC with only logic gates in it.
  •  This gate-level representation of the circuit is converted into a geometric representation of shapes which when manufactured in the corresponding layers of materials will ensure a circuit of transistors doing the intended functionality, called physical design (to generate photomask).
  • Physical Design & Verification:
    • Ready to go to plants (Tape out)
    • Physical Design Process:


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