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Fiber Amplifier A device made from optical fiber and a pump laser that is

designed to produce stimulated emission of photons at the

signal wavelength leading to an amplified signal. There aretwo major types of fiber amplifiers: Raman amplifiers and

doped fiber amplifi

2 Amplifier An amplifier converts an input signal (usually low level intoa larger version of itself. An amplifier device provides thisconversion process. Amplifiers increase both the desired

signal and unwanted noise signals. !oise signals are any

random disturban

" #lass A$

Amplifier 

An amplifier that is operating in class A$. #lass A$

amplifiers can amplify between %&' degrees to "' degrees of

the input signal (somewhat non)linear.

* #lass #Amplifier 

An amplifier that is operating in class #. #lass # amplifierscan amplify a signal for less than %&' degrees of its input

cycle (non)linear amplification for a majority of portions of

the input signal.

+ #lass $

Amplifier 

An amplifier that is operating in class $. #lass $ amplifiers

can amplify a signal for %&' degrees of its input cycle (non)

linear amplification for particular portions of the input signal.

Amplified,andset

A handset (microphone and spea-er that contains anintegrated (built)in amplifier. Amplified handsets may be

used by the hearing impaired.

/ideo Amplifier An amplifier designed to operate over the band of fre0uencies

used for T/ signals.

& /ariable 1ain

Amplifier 

An amplifier whose gain can be controlled by an eternal

signal source.

3 Tuned Radio

Fre0uencyAmplifier 

An amplifier that operates at a specific (tuned radio

fre0uency.

%' 4hototransistor A transistor that detects light energy and amplifies the

resulting electrical signal. 5ight falling on the base)collector junction generates a current which is amplified internally.

%% 4raseodymium

6oped Fiber

Amplifier

(46FA

A device used to amplify signals across a broad range of

wavelengths in an optical networ-. This device is very similar

to the 7rbium 6oped Fiber Amplifier (76FA. 4raseodymium

doping causes the metastable electrons to have the rightenergy to enable st

%2 5ow !oise

Amplifier (5!A

A sensitive pre)amplifier used at a focal point (the feedhorn

of a satellite antenna to strengthen the wea- satellite signal.The most important parameter of the 5!A is its noise

temperature as described in degrees 8elvin. 9n general the

lower the noi

%" agnetic An amplifier that uses magnetic fields to amplify signals.

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Amplifier 

%* ,eadend 6river

Amplifier 

An amplifier that is used in a cable television networ- to

increase the level of the RF signal for supply to thedistribution networ-.

%+ 7ternal RF

4ower Amplifier8it

An assembly or number of electronic parts that can be

attached to a transmitter as an eternal RF power amplifiereven if additional parts are re0uired to complete assembly.

% 6egeneration (%)recording The loss of 0uality on a videotape typically

resulting from multiple generations of copying the material.

(2)amplifier circuit The process of reducing the gain of an

amplifier stage by applying negative feedbac- (feedbac- thatis 3; degree

% #ommon ode

Range

The amplitude of the common mode signal that can be applied

to the two differential inputs of an amplifier and maintain its performance. (<ee also: differential amplifier.

%& #urrentAmplifier 

A low output impedance amplifier capable of providing highcurrent output.

%3 #lass AAmplifier 

An amplifier that is operating in class A (fully linear.

2% ;ptical

Amplifier (;A

A means of amplifying an optical signal through the sensing

of energy at particular optical wavelengths and adding optical

energy at the same wavelength so the resultant signal is areplica of the input signal at higher (amplified energy level.

The most

2+ 4ump 5aser A laser used to prime a fiber amplifier so that stimulatedemission can ta-e place. The laser pumps the energy of

electrons in the fiber up to a high energy state called the pump

state. They then decay to the metastable state where they can

interact with

2 8lystrode An amplifier device for =,F)T/ signals that combines

aspects of a tetrode (grid modulation with a -lystron (velocity

modulation of an electron beam. The result is a more efficientless epensive device for many applications. 8lystrode is a

trademar- of 

2 9sophasing

Amplifier 

A timing device that corrects for small timing errors.

2& 7rbium 6opedFiber Amplifier

(76FA

A device used to amplify signals across a broad range ofwavelengths in an optical networ-. The ability to amplify

more than one wavelength at a time made >avelength

6ivision ultipleing (>6 practical. 76FAs are used to boost signals at the transmitt

23 7ternal RF

4ower Amplifier 

A device that is capable of increasing power output when used

in conjunction with but not an integral part of a transmitter.

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"' 6oped Fiber

Amplifier (6FA

A device used to amplify signals across a broad range of

wavelengths in an optical networ-. The ability to amplify

more than one wavelength at a time made >avelength6ivision ultipleing (>6 practical. A 6FA consists of a

 pump laser a length of doped

"% Amplitudeodulator <tage

The last amplifier stage in a transmitter where the assembly(stage modulates a radio)fre0uency signal.

"2 Active ,ub A device that amplifies transmission signals in a networ-

allowing signals to be sent over a much greater distance than

is possible with a passive hub. An active hub may have portsfor coaial twisted)pair or fiber)optic cable connections as

well as

"" Amplifier

 !onliearity

An indicator of distortion that is caused by inconsistent

amplification (higher or lower gain to different levels orfre0uencies of input signals of a device or system.

*+ TelevisionReceive ;nly(T/R;

A ground station used for the reception of T/ signalstransmitted from satellites. A typical station consists of a parabolic dish antenna pre)amplifier down)converter tunable

receiver and video monitor.

* <ound Analy?er An instrument consisting of a microphone amplifier and wave

analy?er used to measure the amplitude and fre0uency of thecomponents of a comple sound.

* <lew Rate The maimum rate of change of the output voltage of an

amplifier operated within its linear region.

*& RegenerativeRepeater 

A repeater that receives amplifies reshapes and retransmitsdigital signals.

*3 ;ptical Repeater A networ- element that receives and retransmits optical

signals after enhancing or regenerating the signal. ;ptical

Repeaters can be all)optical if the signal only needs to beamplified. For more sophisticated regeneration the optical

signal is convert

+' !oise Figure A measure of the noise in decibels generated at the input of anamplifier compared with the noise generated by an impedance

method resistor at a specified temperature.

+% ultivibrator (%)general A relaation oscillator with the outputs from each

of two amplifying stages fed bac- in phase to the input stage

of the other amplifier to produce oscillation. (2)free)runningA multivibrator that operates without eternal triggering or s

+2 odulation

 !oise

9ntermodulation distortion in an analog amplifier or modulator 

whose level varies as the input power changes or from otherdistortions.

+" #ommon ode <ignals identical with respect to amplitude fre0uency and

 phase that are applied to both terminals of a cable and@or boththe input and reference of an amplifier.

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+* #ommon ode

Rejection (#R

A measure of how well a differential amplifier rejects a signal

that appears simultaneously and in phase at both input

terminals. As a specification #R usually is stated as adecibel ratio at a given fre0uency.

++ #ell 7tender A cellular system repeater that re)transmits base station

channels. A cell etender could be considered nothing morethan a linear amplifier.

+ =nbalanced A condition of circuits or lines in which the impedance of one

side of the terminal differs from that of the other side of the

same terminal. 7amples include a cable pair in which theimpedance of the ring and tip differ and an amplifier in which

one of 

+ Repeater (%)general A device or circuit that is located between

transmitting and receiving devices to improve the 0uality thesignal that is delivered between them. A repeater obtains some

or all of the signal from the transmitter amplifies and may

adjust (chang

+& 4ump The energy source used to drive electrons up to a high energy

state called the pump level. From the pump level the electrons

lose energy and reach the metastable state needed for

stimulated emission. 5asers and fiber amplifiers must be pumped before sti

+3 !egative

Feedbac- 

The return (feedbac- of an output signal that subtracts (adds

%&' degrees out of phase. from the output signal. !egativefeedbac- decreases the output signal amplitude and usually

stabili?es the amplifier. This may result in reduced distortion

and noise' 5oad (%)general The wor- re0uired of an electrical or mechanical

system. (2)data The process of inputting programs or data to

a computer for storage or manipulation. (")device output A

circuit or device that receives the output of an amplifier ortransmis

% Analog <ignal

4rocessing

Analog signal processing involves the conversion of analog

signals into another form using analog (continuous circuits or 

systems. Analog signal processing includes filters shapingcircuits combiners and amplifiers to change their shape and

modify th