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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).
Transistor–transistor logic uses bipolar transistors to form its integrated circuits. [12] TTL has changed significantly over the years, with newer versions replacing the older types. Since the transistors of a standard TTL gate are saturated switches, minority carrier storage time in each junction limits the switching speed of the device.
The threshold values at the input to a logic gate determine whether a particular input is interpreted as a logic 0 or a logic 1 (e.g. anything less than 1 V is a logic 0, and anything above 3 V is a logic 1; in this example, the threshold values are 1 V and 3 V).
RTL is the earliest class of transistorized digital logic circuit; it was succeeded by diode–transistor logic (DTL) and transistor–transistor logic (TTL). RTL circuits were first constructed with discrete components, but in 1961 it became the first digital logic family to be produced as a monolithic integrated circuit.
In NMOS logic, the lower half of the CMOS circuit is used in combination with a load device or pull-up transistor (typically a depletion load or a dynamic load). AOI gates are similarly efficient in transistor–transistor logic (TTL). Examples. CMOS 4000-series logic family: CD4085B = dual 2-2 AOI gate [4] CD4086B = single expandable 2-2-2-2 ...
7400 series parts were constructed using bipolar junction transistors (BJT), forming what is referred to as transistor–transistor logic or TTL. Newer series, more or less compatible in function and logic level with the original parts, use CMOS technology or a combination of the two ( BiCMOS ).
A multiple-emitter transistor is a specialized bipolar transistor mostly used at the inputs of integrated circuit TTL NAND logic gates. Input signals are applied to the emitters . The voltage presented to the following stage is pulled low if any one or more of the base–emitter junctions is forward biased, allowing logical operations to be ...
Differential TTL is a type of binary electrical signaling based on the transistor-transistor logic (TTL) concept. It enables electronic systems to be relatively immune to noise. [ 1 ] RS-422 and RS-485 outputs can be implemented as differential TTL.