Amplifiers

Vacuum-tube amplifiers An ECC83 tube glowing inside a preamp main Vacuum-tube amplifiers (also known as tube amplifiers or valve amplifiers) use a vacuum tube as the active device.

Transistor amplifiers seeAlso Transistor amplifiers (or solid state amplifiers) are the most common type of amplifier in use today.

While semiconductor amplifiers have largely displaced valve amplifiers for low power applications, valve amplifiers can be much more cost effective in high power applications such as radar, countermeasures equipment, and communications equipment.

One of the key differences between HDMI distribution amplifiers and HDMI splitters is that amplifiers can boost the signal, while splitters cannot.

An early use of class-D amplifiers was high-power subwoofer amplifiers in cars.

Applications Video amplifiers Video amplifiers are designed to process video signals and have varying bandwidths depending on whether the video signal is for SDTV, EDTV, HDTV 720p or 1080i/p etc..

Class-D amplifiers are widely used to control motors —but are now also used as power amplifiers, with extra circuitry that converts analogue to a much higher frequency pulse width modulated signal.

Class-D amplifiers for driving subwoofers are relatively inexpensive in comparison to class-AB amplifiers.

Class-G amplifiers (which use "rail switching" to decrease power consumption and increase efficiency) are more efficient than class-AB amplifiers.

DC imperfections Real operational amplifiers suffer from several non-ideal effects: ;Finite gain: Open-loop gain is infinite in the ideal operational amplifier but finite in real operational amplifiers.

Guitar amplifiers are designed with a different approach than that used to design sound reinforcement system power amplifiers and home "hi-fi" stereo systems.

Most low-end and mid-range amplifiers omit the phono input ; but on the other hand, low-end turntables with built-in phono pre-amplifiers are widely available.

Negative resistance devices Negative resistances can be used as amplifiers, such as the tunnel diode amplifier. citation citation Amplifier architectures Amplifiers can also be categorised by the way they amplify the input signal.

One is by the frequency of the electronic signal being amplified; audio amplifiers amplify signals in the audio (sound) range of less than 20 kHz, RF amplifiers amplify frequencies in the radio frequency range between 20 kHz and 300 GHz.

Radio-frequency amplifiers up to the UHF spectrum use MOSFET transistors as analog signal and power amplifiers.

Semiconductor optical amplifier Semiconductor optical amplifiers (SOAs) are amplifiers which use a semiconductor to provide the gain medium.

Signal and audio transformers are used to couple stages of amplifiers and to match devices such as microphones and record players to the input of amplifiers.

Switched mode amplifiers These nonlinear amplifiers have much higher efficiencies than linear amps, and are used where the power saving justifies the extra complexity.

Telephone repeater Before the invention of electronic amplifiers, mechanically coupled carbon microphones were used as amplifiers in telephone repeaters.

The principal difference between C- and L-band amplifiers is that a longer length of doped fibre is used in L-band amplifiers.