ECE 275: Digital Design I

Class 4
  • SSI - Small Scale Integration (~50 transistors) - Logic gates
  • MSI - Medium Scale Integration (50-500 transistors) - Flip Flops
  • LSI - Large Scale Integration (500-50K) - Larger memory components
  • VLSI - Very Large Scale Integration (500,000) - Processors Cache

Gordon Moore (Moore's Law)

Double the amount of transistors in the same chip area over ~18 months

IC Logic Families

Characteristics
  1. Fan Out - How many gates can the output drive? Buffer = Not gate without the not. Given 1, it outputs 1. Given 0, it outputs 0 Buffer has a fan out of 50-70 gates
  2. Propagation Delay - How long the gate takes to change after updating the input Usually in the order of picoseconds
TTL ECL CMOS
Fan Out 1-10 20-30 750
PD 1-3ons 1-6ns 1-210ns
Power 10nW 50mW 0.01mW