Signalamplifiers

Signalamplifiers, commonly written as signal amplifiers, are electronic devices that increase the amplitude of a signal while preserving its information content. Amplification is accomplished by supplying energy from a power source to the signal, with careful design to minimize added noise and distortion. Amplifiers are used across audio, radio, and measurement systems.

Electronic amplifiers handle electrical signals. They include low-noise amplifiers at the front end of receivers, voltage and transconductance amplifiers, and power amplifiers for higher output. Optical signal amplifiers boost light signals in fiber optic systems, such as erbium-doped fiber amplifiers (EDFAs) and semiconductor optical amplifiers (SOAs).

Performance is described by several parameters: gain (voltage, current, or power), bandwidth, noise figure, linearity, and impedance. Important constraints include stability, input/output matching, and distortion. In RF design, specifications like gain-bandwidth product, IP3, and compression point (P1dB) are used. In optical amplifiers, noise figure, saturation output, and gain spectrum determine usefulness. Amplifier classes affect efficiency and linearity; for example, Class A emphasizes linearity, while high-efficiency classes are common in power amplifiers.

Applications include telecommunications, broadcast and audio systems, instrumentation, radar, and fiber-optic networks. The field has evolved from vacuum-tube amplifiers to transistor-based designs and, later, integrated circuits and photonic devices. Operational amplifiers in analog electronics provide convenient, high-gain voltage amplification with feedback.