Chapter 9

1. Chapter 9 Logic Families and Their Characteristics Part II CMOS, BiCMOS, and ECL 1

2. Objectives You should be able to: • Discuss the differences and proper use of the various subfamilies within both TTL and CMOS ICs. • Describe the reasoning and various techniques for interfacing between the TTL, CMOS, and ECL families of ICs. 3

3. The CMOS Family • MOSFETs • Metal oxide semiconductor field-effect transistors • PMOS and NMOS type substrates 28

4. The CMOS Family • MOSFETs • Higher packing densities than TTL • Millions of memory cells per chip

5. CMOS inverter

6. CMOS NAND and NOR gates

7. The CMOS Family • Handling CMOS devices • Avoid electrostatic discharge (detailed see P348) • CMOS availability • 4000 series - original CMOS line • 40H00 series – faster (but still slower than LS TTL) • 74C00 series - pin compatible with TTL, lower power, but still slower • 74HC00 and 74HCT00 series • Speedy, less power, pin compatible, greater noise immunity and temperature operating range

8. The CMOS Family • CMOS availability • 74- biCMOS series - low power and high speed • 74-low voltage series • See appendix B • Nominal supply voltage of 3.3 V • 74AHC and 74AHCT series • Superior speed • Low power consumption • High output drive current

9. The CMOS Family • 74AVC advanced very-low-voltage CMOS logic • Faster speed • Very low operating voltages • 3.3 V, 2.5 V, 1.8 V, 1.5 V and 1.2 V

10. Emitter-Coupled Logic • Extremely fast (0.8 ns) • Increased power dissipation • Uses differential amplifiers Figure 9-22

11. Emitter-Coupled Logic

12. Comparing Logic Families • Performance specifications

13. Comparing Logic Families • Propagation delay versus power

14. Comparing Logic Families • Power supply current versus frequency

15. Interfacing Logic Families • TTL to CMOS • Low output of TTL: OK • High output of TTL: not OK

16. Interfacing Logic Families • TTL to CMOS • Pull-up resistor

17. Interfacing Logic Families • CMOS to TTL • No problem with voltages • But concerns on currents

18. Interfacing Logic Families • CMOS to TTL

19. Interfacing Logic Families • Worse-case values • See Table 9-4 in your text.

20. Interfacing Logic Families • Level Shifting • Level-shifter ICs: 4049B and 4050B CMOS TTL

21. Interfacing Logic Families • Level Shifting • Level-shifter ICs: 4504B TTL 5V CMOS 15V

22. Interfacing Logic Families • ECL Interfacing

23. Summary • The CMOS family uses complementary metal oxide semiconductor transistors instead of the bipolar transistors used in TTL ICs. Traditionally, the CMOS family consumed less power but was slower than TTL. However, recent advances in both technologies have narrowed the differences.

24. Summary • The BiCMOS family combines the best characteristics of bipolar technology and CMOS technology to provide logic functions that are optimized for the high-speed, low-power characteristics required in microprocessor systems.

25. Summary • A figure of merit of IC families is the product of their propagation delay and power consumption, called the speed-power product (the lower, the better). • Emitter-coupled logic (ECL) provides the highest-speed ICs. Its drawback is its very high power consumption.

26. Summary • When interfacing logic families, several considerations must be made. The output voltage level of one family must be high and low enough to meet the input requirements of the receiving family. Also, the output current capability of the driving gate must be high enough for the input draw of the receiving gate or gates.