TABLE OF CONTENTS Objective: This chapter describes the main logic families, including BJT-based as well as MOS-based architectures. In the former, DTL, TTL, and ECL are included. In the latter, not only is the traditional CMOS architecture presented but also pseudo-nMOS logic, transmission-gate logic, footed and unfooted dynamic logic, domino logic, C 2MOS logic, and BiCMOS logic. Additionally, a section describing modern I/O standards, necessary to access such ICs, is also included, in which LVCMOS, SSTL, HSTL, and LVDS I/Os are described, among others.
Chapter Contents
| 10.1 | BJT-Based Logic Families |
| 10.2 | Diode-Transistor Logic |
| 10.3 | Transistor-Transistor Logic (TTL) |
| 10.4 | Emitter-Coupled Logic |
| 10.5 | MOS-Based Logic Families |
| 10.6 | CMOS Logic |
| 10.7 | Other Static MOS Architectures |
| 10.8 | Dynamic MOS Architectures |
| 10.9 | Modern I/O Standards |
| 10.10 | Exercises |
The first part of this chapter (Sections 10.2 to 10.4) describes logic circuits constructed with BJTs (bipolar junction transistors).
Digital ICs sharing the same overall circuit architecture and electrical specifications constitute a digital logic family. The first digital families (DTL, TTL, and ECL) were constructed with BJTs. However, the large silicon area required to construct the components of these families (transistors plus associated resistors), and especially their high power consumption, led to their almost complete replacement with MOSFET-based families.
In spite of the limitations above, the analysis of BJT-based families is important because it helps us to understand the evolution of digital technology. Moreover, one of the BJT-based families, called ECL (emitter-coupled logic), is still in use and is the fastest of all...
