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The first CMOS family of logic integrated circuits was introduced by RCA as CD4000 COS/MOS, the 4000 series, in 1968. Initially CMOS logic was slower than LS-TTL. However, because the logic thresholds of CMOS were proportional to the power supply voltage, CMOS devices were well-adapted to battery-operated systems with simple power supplies.
His patent also showed how the Schottky transistor could be used in DTL circuits and improve the switching speed of saturated logic designs, such as the Schottky-TTL, at a low cost. In 1971, Texas Instruments introduced the 74S TTL logic family with Schottky diodes. Later, it was included in the 74LS, 74AS, 74ALS, 74F TTL logic families too.
Transistor–transistor logic (TTL) is a logic family built from bipolar junction transistors.Its name signifies that transistors perform both the logic function (the first "transistor") and the amplifying function (the second "transistor"), as opposed to earlier resistor–transistor logic (RTL) and diode–transistor logic (DTL).
(TTL has the input high level above 2.0 V and the input low level below 0.8 V, so a TTL high-level signal could be in the forbidden middle range for 5 V CMOS.) The 74H family is the same basic design as the 7400 family with resistor values reduced.
A few alphabetic characters to designate a specific logic subfamily may immediately follow the 74 or 54 in the part number, e.g., 74LS74 for low-power Schottky. Some CMOS parts such as 74HCT74 for high-speed CMOS with TTL-compatible input thresholds are functionally similar to the TTL part. Not all functions are available in all families.
The 4000 series was introduced as the CD4000 COS/MOS series in 1968 by RCA [1] as a lower power and more versatile alternative to the 7400 series of transistor-transistor logic (TTL) chips. The logic functions were implemented with the newly introduced Complementary Metal–Oxide–Semiconductor (CMOS) technology.
Current mode logic (CML), or source-coupled logic (SCL), is a digital design style used both for logic gates and for board-level digital signaling of digital data. The basic principle of CML is that current from a constant current generator is steered between two alternate paths depending on whether a logic zero or logic one is being represented.
Diode–transistor logic (DTL) is a class of digital circuits that is the direct ancestor of transistor–transistor logic. It is called so because the logic gating functions AND and OR are performed by diode logic , while logical inversion (NOT) and amplification (providing signal restoration) is performed by a transistor (in contrast with ...