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.

Verilog

• 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: