A multiple-emitter transistor is a specialized

bipolar transistor A bipolar junction transistor (BJT) is a type of transistor that uses both electrons and electron holes as charge carriers. In contrast, a unipolar transistor, such as a field-effect transistor, uses only one kind of charge carrier. A bipola ...

mostly used at the inputs of integrated circuit TTL NAND

logic gate A logic gate is an idealized or physical device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. Depending on the context, the term may refer to an ideal logic ga ...

s. 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 performed using a single

transistor upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch ...

. Multiple-emitter transistors replace the diodes of

diode–transistor logic 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 function (e.g., AND) is performed by a diode network and the amplifying functio ...

(DTL) to make

transistor–transistor logic 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 o ...

(TTL), and thereby allow reduction of

switching time For a frequency synthesizer, the switching time or more colloquially the switching speed is the amount of time from when the command for the next frequency is requested until the time that the synthesizer's output becomes usable and meets the speci ...

and power dissipation. Simple bipolar transistor

Logic gate use of multiple-emitter transistors was patented in 1961 in the UK and in the US in 1962.B. A. Boulter, ''The Multiple Emitter Transistor In Low Power Logic Circuits'' in Edward Keonjian (ed) ''Micropower Electronics'', Elsevier, 2013, , p. 105 ff

References

External links

Tutorial on bipolar-transistor logic
Digital electronics {{physics-stub