Loop Gain

Loop gain is a measure of the gain of a system controlled by feedback loops. As such, the concept of loop gain is useful in a variety of disciplines. Traditionally, most of those have been in the fields of electronics, telecommunications, or (electronic or non-electronic) control systems. It is also useful in biology.

In amplifiers with feedback, loop gain is the product of the gain in the feedback loop and the feedback factor in that loop.

In telecommunications, loop gain can be either of:

  1. The total usable power gain of a carrier terminal or two-wire repeater. The maximum usable gain is determined by, and may not exceed, the losses in the closed path.
  2. The sum of the gains, expressed in dB, acting on a signal passing around a closed path, i.e., a loop.

This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).

Other articles related to "gain, loop gain, loop":

Operational Amplifier - Op-amp Characteristics - Real Op-amps - AC Imperfections
... The op-amp gain calculated at DC does not apply at higher frequencies ... approximation, the op-amp has the frequency response of an integrator with gain ... That is, the gain of a typical op-amp is inversely proportional to frequency and is characterized by its gain–bandwidth product (GBWP) ...
Bode Plot - Gain Margin and Phase Margin
... plots are used to assess the stability of negative feedback amplifiers by finding the gain and phase margins of an amplifier ... The notion of gain and phase margin is based upon the gain expression for a negative feedback amplifier given by where AFB is the gain of the amplifier with feedback (the closed-loop gain ... The gain AOL is a complex function of frequency, with both magnitude and phase ...
Frequency Compensation - Use in Operational Amplifiers
... The amplifier will oscillate if it has a gain of one or more at this critical frequency ... additional -180° to the output phase making the total phase shift -360° and (b) the gain is sufficient to induce oscillation ... will oscillate at the frequency at which its open loop gain equals its closed loop gain if, at that frequency, 1 ...
Operational Amplifier - Op-amp Characteristics - Real Op-amps - DC Imperfections
... suffer from several non-ideal effects Finite gain Open-loop gain is infinite in the ideal operational amplifier but finite in real operational amplifiers ... Typical devices exhibit open-loop DC gain ranging from 100,000 to over 1 million ... So long as the loop gain (i.e ...

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