emitter follower

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emitter follower

[i′mid·ər ‚fäl·ə·wər]
(electronics)
A grounded-collector transistor amplifier which provides less than unity voltage gain but high input resistance and low output resistance, and which is similar to a cathode follower in its operations.

Emitter follower

A circuit that uses a common-collector transistor amplifier stage with unity voltage gain, large input resistance Ri, and small output resistance Ro (see illustration). In its behavior, the emitter follower is analogous and very similar to the source follower in metal-oxide-semiconductor (MOS) circuits. Many electronic circuits have a relatively high output resistances and cannot deliver adequate power to a low-resistance load, or do suffer unacceptable voltage attenuation. In these cases, an emitter follower acts as a very simple buffer. Widely used, it is often found as the last stage of a multistage amplifier so that the circuit is better able to drive a low-resistance load. See Amplifier

Schematic diagram of an emitter follower circuitenlarge picture
Schematic diagram of an emitter follower circuit
References in periodicals archive ?
The reason for the similarity is that the loaded Q of the oscillator is high (Q = 37 for the common collector oscillator and Q = 19 for the common base oscillator).
and yes, I've always mispronounced it too) is not a common collector piece today.
Optocouplers can provide isolation benefits for many possible circuits, but for this article we will assume a simple common collector configuration for the phototransistor output.
Measurements were done at nominal room temperature using the common collector circuit configuration and operating at 5 V.
These techniques are applied to the analysis of small signal [pi] and T transistor representative circuits in the CE, CB, and common collector configurations with reference to a program developed by the author.
To simplify design, all versions of these quad devices share common collector pins on the output transistors.