Digital Logic Fundamentals Unit 8 – TTL and CMOS Comparison
CMOS gates have a nominal positive supply voltage (VDD) of 5 Vdc, 10 Vdc, and 15 Vdc (3
Vdc to 18 Vdc). The negative supply voltage (VSS) is less than the input or output voltages.
Special types of CMOS gates, called high speed CMOS gates, combine the speed of TTL gates
with the low power requirements of CMOS gates.
CMOS devices are available in B series (buffered) or UB series (unbuffered) versions. UB
devices are generally faster than B series devices, but they possess less ideal noise immunity and
transfer characteristics.
HANDLING
TTL gates are not considered to be sensitive to static electricity. CMOS gates are very static
sensitive devices that can be damaged or destroyed by improper handling.