Digital Logic Fundamentals Unit 8 – TTL and CMOS Comparison
NEW TERMS AND WORDS
VDD - the higher potential (with respect to Vss) power supply voltage of CMOS devices.
VSS - the lower (in potential) of two supply voltages required for a TTL IC.
high speed CMOS gates - a family of devices that combines the speed of TTL circuits with the
low power requirements for CMOS.
B series - CMOS gates that possess higher
UB series - CMOS gates that possess lower gain and less ideal transfer characteristics than
buffered CMOS devices do.
transition time - the time it takes the output to go between 10% and 90% of the maximum output
voltage; tTHL and tTLH are the symbols for transition time.
propagation delay - the time between the 50% point of the input signal and the 50% point of the
output signal; tPHL and tPLH are the symbols for propagation delay.
tTHL - the symbol for high-to-low transition time.
tTLH - the symbol for low-to-high transition time.
tPHL - the symbol for high-to-low propagation delay.
tPLH - the symbol for low-to-high propagation delay.
EQUIPMENT REQUIRED
F.A.C.E.T. base unit
DIGITAL LOGIC FUNDAMENTALS circuit board
Multimeter
Oscilloscope, dual trace