Compare the various logic families with respect to their characteristics. Give at least five points with their practical values

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written 3.6 years ago by

teamques10 ★ 68k

The various logic families are Transistor-Transistor logic, CMOS logic, ECL logic families.

TTL [Transistor-Transistor logic]

ECL [Emitter-Coupled logic]

BJTs operating in unsaturated mode (i.e. emitter-follower mode).
Principle: Current switching [ECL is also sometimes called Current Mode logic].
Disadvantages:
- Negative supply
- High state power dissipation
- Low noise marge

Characteristic value:

Family	Basic gate	Fanout	Pd(mW/gate)	Noise immunity	Propagation delay	Clock(MHz)
TTL	NAND	10	10	Very good	10	35
TTL-H	NAND	10	22	Very good	6	50
ECL-10K	OR-NOR	25	40-55	Poor	2	>60
ECL-100K	OR-NOR	-	40-55	Poor	0.75	600
MOS	NAND	20	0.2-10	Good	300	2
74C	NOR/NAND	50	0.01/1	Very good	70	10
74HC	NOR/NAND	20	0.0025	Very good	18	60

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