1. M.Mohajjel

2. Digital Systems Advantages Ease of design Reproducibility of results Noise immunity Ease of Integration Disadvantages The real world is analog A/D & D/A overhead 2Digital System Design

3. Evolution of Digital Systems The earliest digital circuits vacuum tubes & transistors Integrated circuits SSI (Small Scale Integration) 10s of logic gates MSI (Medium Scale Integration) 100s of logic gates LSI (Large Scale Integration) 1000s of logic gates VLSI (Very Large Scale Integration) 100,000s of logic gates Need for Computer-Aided Design 3Digital System Design

4. Digital System Design Process Initial design idea Behavioral description (overall functionality) Flow chart Pseudo code RTL description Data path Control procedure 4Digital System Design

5. Digital System Design Process (cont.) Logic design Net list of gates & flip flops Circuit & Physical design Net list of transistors Manufacturing Masks for IC Fabrication Bit stream 5Digital System Design

6. Digital System Design Process (cont.) Synthesis Verification Computer aided design (CAD) tools Synthesis From RTL description down to manufacturing Verification Simulation Timing analysis Test generation 6Digital System Design

7. Programmable Logic Devices Why? TTM (Time-to-market) Prototyping Reconfigurable and Custom Computing 7Digital System Design

8. Hardware Description Languages (HDL) Why? Very large scale designs Weakness of conventional programming language in hardware modeling and description Compact description of hardware in different design stages 8Digital System Design

9. Hardware Description Languages (HDL) (cont.) Hardware Description Requirements Concurrency Timing and Delay Support for Design Hierarchy Readability (Documentation) 9Digital System Design

10. Hardware Description Languages (HDL) (cont.) Examples Popular HDLs (IEEE standard) Verilog = Verifying Logic VHDL = Very High Speed Integrated Circuit Hardware Description Language Other HDLs AHPL TI-HDL AHDL 10Digital System Design