03-05-2013, 04:09 PM
TTL And CMOS Comparison
TTL And CMOS.doc (Size: 94.5 KB / Downloads: 19)
Abstract
The information contained herein documents the experiment performed by James Poe and a small group of Logic Design students on two separate dates, September 13th and 16th, of the year 2002. This experiment was designed to compare the operation of two different forms of manufacturing IC logic chips, namely TTL and CMOS. The experiment was completed successfully, with the expected results achieved. The list of equipment used is contained within an attached appendix.
Introduction
In the world of digital design, and really all forms of integrated circuit technology, there are several distinct logic families based on the internal structure of the chips. A few of these families include Metal-Oxide Semiconductor (MOS ), Emitter-Coupled Logic (ECL), Transistor-Transistor Logic (TTL), and Complementary Metal-Oxide Semiconductor (CMOS). In this lab, the differences and similarities of the two that are probably most common will be explored, TTL and CMOS. To discover these differences, current and voltage will be applied to single and series logic inverter gates from both families, and results such as propagation delay and power consumption will be measured across the circuit. It is expected that the TTL will function faster than the CMOS, but with higher power consumption levels. Other differences exist between the two chips such as the noise margin, however our current equipment lacks the sensitivity to test such properties.
Conclusion
After completing the lab, the student now has a well grounded perspective on the functionality of both CMOS and TTL fabricated logic designs. While both appear to be identical macroscopically, it can be seen as proved through this experiment, rather large differences do exist. The TTL functioned nearly 6 times faster than the same CMOS chip, however consumed almost double the power. One result that was not expected personally was that the CMOS would deliver more precise results (i.e. it registered almost exactly 5 volts for the high voltage, and a lower low voltage than the equivalent TTL). I feel that further personal investigation is necessary to reveal if this was a simple coincidence, or a well documented trend.