Circuit Design: Know It All

Chapter 7

Digital Circuit Fundamentals

Ian Grout

Early electronic circuits were analog, and before the advent of digital logic, signal processing was undertaken using analog electronic circuits. The invention of the semiconductor transistor in 1947 at Bell Laboratories [Ref. 7.1] and the improvements in transistor characteristics and fabrication during the 1950s led to the introduction of linear (analog) ICs and the first transistor-transistor logic (TTL) digital logic IC in the early 1960s, closely followed by complementary metal-oxide semiconductor (CMOS) ICs. The early devices incorporated a small number of logic gates. However, rapid growth in the ability to fabricate an increasing number of logic gates in a single IC led to the microprocessor ...