In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor ( BJT ) amplifier topologies, typically used as a voltage amplifier.

The analogous bipolar junction transistor circuit is the common-emitter amplifier.

Collector current is approximately β ( common-emitter current gain ) times the base current.

The common-emitter current gain is represented by β < sub > F </ sub > or h < sub > FE </ sub >; it is approximately the ratio of the DC collector current to the DC base current in forward-active region.

However, it is popular in high-frequency amplifiers, for example for VHF and UHF, because its input capacitance does not suffer from the Miller effect, which degrades the bandwidth of the common-emitter configuration, and because of the relatively high isolation between the input and output.

Often a common base is used in this manner, preceded by a common-emitter stage.

The emitter current source is usually implemented as a common-emitter transistor stage with constant base voltage driving with current the two common-base transistor stages.

It is interesting fact that the basic input logical operation OR is performed by applying consecutively the two arithmetic operations addition and comparison ( the input resistor network acts as a parallel voltage summer with equally weighted inputs and the next common-emitter transistor stage-as a voltage comparator with a threshold about 0. 7 V ).

The two transistors mutually ground their emitters ; so, although they are common-collector stages, they actually act as common-emitter stages with maximum gain.

At differential mode, they behave as common-emitter stages with grounded emitters ; so, the input impedances are low.

It consists of a common-emitter stage with a base resistor connected between the base and the input voltage source.

The DTL circuit shown in the picture consists of three stages: an input diode logic stage ( D1, D2 and R1 ), an intermediate level shifting stage ( R3, R4 and V -) and an output common-emitter switching-transistor stage ( Q1 and R2 ).

This configuration gives a much higher common-emitter current gain than each transistor taken separately and, in the case of integrated devices, can take less space than two individual transistors because they can use a shared collector.

Amplifier circuit, common-emitter configuration with a voltage-divider bias circuit.

Figure 1: Basic NPN common-emitter circuit ( neglecting biasing details ).

One of the most desirable solutions is achieved by the use of a non-linear amplifier for Af.

The amplifier is designed so that its gain is large for accelerometer signals above a certain threshold level.

Below this level, the amplifier gain Af is proportional and is of small value, in order to provide adequate noise filtering.

When the system is on automatic leveling, the gyro drift is canceled by the output of the leveling system ( amplifier Af ).

Another feature to make LS AAS element-specific is modulation of the primary radiation and the use of a selective amplifier that is tuned to the same modulation frequency, as already postulated by Alan Walsh.

An amplifier is a device for increasing the power of a signal by use of an external energy source.

In an electronic amplifier, the input " signal " is usually a voltage or a current.

The gain of an amplifier is the ratio of output to input power or amplitude, and is usually measured in decibels.

The bandwidth of an amplifier is the range of frequencies for which the amplifier gives " satisfactory performance ".

Based on this definition, the drain efficiency cannot exceed 25 % for a class A amplifier that is supplied drain bias current through resistors ( because RF signal has its zero level at about 50 % of the input DC ).

When the signal drive to the amplifier is increased, the output also increases until a point is reached where some part of the amplifier becomes saturated and cannot produce any more output ; this is called clipping, and results in distortion.

In most amplifiers a reduction in gain takes place before hard clipping occurs ; the result is a compression effect, which ( if the amplifier is an audio amplifier ) sounds much less unpleasant to the ear.

In 2006 Marshall designed new, prototype versions of " Murder One " which were then put into production, and the original amplifier was retired.

A Los Angeles radio manufacturer named Van Nest designed the first Electro String production-model amplifier.

In a well designed receive chain, only the noise factor of the first amplifier should be significant.

While originally designed to handle logic-level digital signals, a TTL inverter can be biased as an analog amplifier.

Another technique to exhaust victim resources is through the use of an attack amplifier — where the attacker takes advantage of poorly designed protocols on 3rd party machines, such as FTP or DNS, in order to instruct these hosts to launch the flood.

Poorly designed horns, or improperly crossed-over horns, have predictable problems in the accuracy of their output, and the load that they present to the amplifier.

Normally the crossover and speaker system, including the woofer, are expected to convert the electrical signal supplied by the amplifier to an acoustic signal of identical waveform without other interaction between the amplifier and speakers, although sometimes the amplifier and speakers are designed together with the speakers supplying distortion-correcting negative feedback to the amplifier.

They added a motion sensor to the woofer, and used the signal corresponding to its actual motion to feedback as a control input to a specially designed amplifier.

Woofers designed for public address system ( PA ) and instrument amplifier applications are similar in makeup to home audio woofers, except that they are usually designed more ruggedly.

This includes its massive horn loudspeakers designed to fill a large theater with sound from a relatively low-powered tube amplifier.

The guitars, bass guitars, and amplifiers he designed from the 1940s on are still relevant: the Fender Telecaster ( 1950 ) was the first mass-produced electric guitar ; the Fender Stratocaster ( 1954 ) is among the world's most iconic electric guitars ; the Fender Precision Bass ( 1951 ) set the standard for electric bass guitars ; and the Fender Bassman amplifier, popular enough in its own right, became the basis for later amplifiers ( notably by Marshall and Mesa Boogie ) that dominated rock and roll music.

In 1945, they began selling the guitar, in a kit with an amplifier designed by Fender.

The original video amplifier circuit path on the motherboard was poorly designed and created faint black lines in the game image.

This type of amplifier is available in a range of formats, ranging from smaller combo amplifiers for rehearsal and warm-up purposes to heavy " heads " which are designed to be used with separate speaker cabinets, which is colloquially referred to as a " stack.

The exception to this rule is keyboard amplifiers designed for the Hammond organ, such as the vintage Leslie speaker cabinet and modern recreations, which have a tube amplifier which is often turned up to add a warm, " growling " overdrive to the organ sound.

They are similar in many ways to keyboard amplifiers, in that they have a relatively flat frequency response, and they are usually designed so that neither the power amplifier nor the speakers will introduce additional coloration.

Feedback-free instrumentation amplifier is the high input impedance differential amplifier designed without the external feedback network.

A guitar amplifier ( or guitar amp ) is an electronic amplifier designed to amplify the electrical signal of an electric or acoustic guitar so that it will produce sound through a loudspeaker.