1. Something that amplifies, enlarges, or extends.
2. In electronics, a device, especially one using transistors or electron tubes, which produces the amplification (increase) of an electrical signal.
3. A device that makes sounds louder; especially, one that increases the sound level of musical instruments.
4. An electronic device that increases the magnitude of a signal, voltage, or electric current.

1. An amplifier circuit characterized by low-current drift and input-current offsets, and adequate power and current sensitivities, such that it is capable of measuring extremely low current variations in a circuit.
2. A low-noise amplifier having sufficiently low current drift and other characteristics required for measuring very low currents.

1. A circuit which uses electron tubes to provide the additional power needed to amplify a signal.
2. An amplifier in which electron tubes provide the required increase in signal strength.

1. A device that boosts a signal by varying the energy pumped from an electrostatic field into an electron beam traveling down the length of a tube, and then manipulating the beam at either end of the tube.
2. A parametric amplifier in which energy is pumped from an electrostatic field into a beam of electrons traveling down the length of the tube, and electron couplers impress the input signal at one end of the tube and translate spiraling electron motion into electric output at the other end.

An amplifier consisting of an electron-gun modulation system, semiconductor target and output coupling network all within a glass or ceramic envelope.

The semiconductor target is a pair of silicon diodes, each consisting of two metallic electrodes with a pn (positive-negative) junction under the top contact.

A pn junction or a diode (one way valve) is a pn junction with p-type (positive-type) on one side and n-type (negative-type) on the other side.

When a positive voltage is applied to the p-type side (forward bias), it shrinks and overcomes the depletion zone, causing the current to flow from the p-type to the n-type side. When a negative voltage is applied to the p-type of the diode (reverse bias), it increases the depletion zone and prevents current from flowing.

The amplifier operation is based on the fact that a modulated electron beam can control the current in a reverse-based semiconductor junction.

1. An electronic circuit whose function is to accept an input voltage and produce a magnified, accurate replica of this voltage as an output voltage.

The voltage gain of the amplifier is the amplitude ratio of the output voltage to the input voltage.

2. An amplifier designed primarily to build up the voltage of a signal or to increase a signal's voltage, without supplying appreciable power.