Loop gain

Loop gain

In negative feedback amplifiers, loop gain refers to the product of the gain in the feedback loop and the feedback factor in that loop. In Figure 1, the loop gain is the product β"A"OL.

In telecommunication, the term loop gain has the following meanings:

1. The total usable power gain of a carrier terminal or two-wire repeater.

"Note:" 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.

Loop gain is an engineering term used to quantify the gain of a system controlled by feedback loops. Respiration is in fact such a system. The gain being influenced by controller variables (hypercapnic and hypoxic responsiveness), the ability to eliminate CO2)and circulation time, among others. Simply put, loop gain can be defined as the response of a system divided by the disturbance leading to that response:

Loop gain = response to a disturbance / the disturbance itself

It should be evident from this formula that ventilation will become quite unstable when loop gain is more than 1. If theresponse is always greater than the disturbance, then ventilation can never stabilize and will wax and wane indefinitely. Thus, the higher the loop gain (the closer it is to 1), the potentially more unstable the respiratory control system will become. In sleep medicine the term loop gain describes the respiratory insetability. Ventilatory insetability is likely to be most important in patients with apnoea with only a mild pharyngeal anatomical deficiency. If these individuals have a high loop gain, then the fluctuating upper airway resistance which occurs at sleep onset may be sufficiently destabilising that ventilation will begin to cycle leading to further loss of pharyngeal muscle activation and frank airway collapse (DP White, 2006; RB Fogel 2004).


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • loop gain — atvirojo kontūro stiprinimo koeficientas statusas T sritis automatika atitikmenys: angl. loop gain; open loop gain vok. Kreisverstärkung, f; Verstärkung des offenen Regelkreises, f; Verstärkung offenen Kreises, f rus. коэффициент усиления… …   Automatikos terminų žodynas

  • loop gain — noun (telecommunication) the gain of a feedback amplifier or system as a function of how much output is fed back to the input if the loop gain is too great the system may go into oscillation • Topics: ↑telecommunication, ↑telecom • Hypernyms:… …   Useful english dictionary

  • Open-loop gain — The open loop gain of an operational amplifier is the gain obtained when no feedback is used in the circuit. Open loop gain is usually exceedingly high; in fact, an ideal operational amplifier has infinite open loop gain. Typically an op amp may… …   Wikipedia

  • open loop gain — atvirojo kontūro stiprinimo koeficientas statusas T sritis automatika atitikmenys: angl. loop gain; open loop gain vok. Kreisverstärkung, f; Verstärkung des offenen Regelkreises, f; Verstärkung offenen Kreises, f rus. коэффициент усиления… …   Automatikos terminų žodynas

  • closed-loop gain — uždaroji valdymo sistema statusas T sritis automatika atitikmenys: angl. closed loop control system; closed loop gain; monitored control system vok. geschlossenes Regelungssystem, n; Regelkreis, m; Regelkreisverstärkung, f; Regelsystem, n rus.… …   Automatikos terminų žodynas

  • Gain — For other uses, see Gain (disambiguation). In electronics, gain is a measure of the ability of a circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output. It is usually defined as the mean ratio of… …   Wikipedia

  • gain en boucle ouverte — atvirojo kontūro stiprinimo koeficientas statusas T sritis automatika atitikmenys: angl. loop gain; open loop gain vok. Kreisverstärkung, f; Verstärkung des offenen Regelkreises, f; Verstärkung offenen Kreises, f rus. коэффициент усиления… …   Automatikos terminų žodynas

  • Gain-bandwidth product — The gain bandwidth product (GBW or GB) for an amplifier is the product of the open loop gain (constant for a given amplifier) and its 3 dB bandwidth. Relevance to design This quantity is commonly specified for operational amplifiers, and allows… …   Wikipedia

  • Loop unwinding — Loop unwinding, also known as loop unrolling, is a loop transformation technique that attempts optimize a program s execution speed at the expense of its size.The goal of loop unwinding is to increase the programs speed by reducing (or… …   Wikipedia

  • Loop antenna — A shortwave loop antenna A loop antenna is a radio antenna consisting of a loop (or loops) of wire, tubing, or other electrical conductor with its ends connected to a balanced transmission line. Within this physical description there are two very …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”