NationMaster - Encyclopedia: Slew rate

In electronics, the slew rate is a nonlinear effect in amplifiers. It represents the maximum rate of change of signal at the amplifier output. The field of electronics is the study and use of systems that operate by controlling the flow of electrons (or other charge carriers) in devices such as thermionic valves and semiconductors. ... To do: 20th century mathematics chaos theory, fractals Lyapunov stability and non-linear control systems non-linear video editing See also: Aleksandr Mikhailovich Lyapunov Dynamical system External links http://www. ... For the British rock band of the same name, see Amplifier (band) An amplifier can be considered to be any device that uses a small amount of energy to control a source of a larger amount of energy, although the term today usually refers to an electronic amplifier. ...

In mechanics the slew rate is given in dimensions 1/T and is associated with the change in position over time of an object which orbits around the observer. Mechanics can be seen as the prime, and even as the original, discipline of physics. ... Dimensional analysis is a conceptual tool often applied in physics, chemistry, and engineering to understand physical situations involving a mix of different kinds of physical quantities. ...

Definition

The slew-rate of an op-amp is defined as the maximum rate of change of the output voltage for all possible input signals.

$mathrm{SR} = max(frac{dv_mathrm{out}(t)}{dt})$

where $v out (t)$ is the output produced by the amplifier as a function of time t.

Slew rate is typically expressed in units of V/µs. Josephson junction array chip developed by NIST as a standard volt. ... A microsecond is an SI unit of time equal to one millionth (10-6) of a second. ...

Measurement

The slew rate can be measured using a function generator and oscilloscope.

Origin of slew rate limiting in operational amplifiers

There are slight differences between different op-amp designs in how the slewing phenomenon occurs. However, the general principles are the same as in this illustration.

The input stage of an op-amp is a differential amplifier with a transconductance characteristic. This means the input stage takes a differential input voltage and produces an output current into the second stage. The transconductance is typically very high — this is where the large gain of the op-amp arises. This also means that a fairly small input voltage can cause the input stage to saturate. In saturation, the stage produces a nearly constant output current. Simple form of a differential amplifier A differential amplifier is a type of an electronic amplifier that multiplies the difference between two inputs by some constant factor (the differential gain). ... Transconductance, also known as mutual conductance, is a property of certain electronic components. ... A differential can mean one of several things: Differential (mathematics) Differential (mechanics) Differential signaling is used to carry high speed digital signals. ... Electric current is the flow of electric charge. ... For magnetic materials, saturation is the state when the material can not absorb a stronger magnetic field, such that an increase of magnetization produces no significant change in magnetic flux density. ... The term saturation generally means thoroughly full, and can refer to the following: In chemistry, see saturation (chemistry) for a number of meanings. ...

The second stage of an op amp is, amongst other things, where frequency compensation is accomplished. The low pass characteristic of this stage approximates an integrator. A constant current input will therefore produce a linearly increasing output. If the second stage has a compensation capacitance $C$ and gain $A 2$ , then slew rate in this example can be expressed as: In electrical engineering, frequency compensation is a design technique for amplifiers which use negative feedback or those, such as operational amplifiers, that are intended for use with negative feedback. ... A low-pass filter is a filter that passes low frequencies well, but attenuates (or reduces) frequencies higher than the cutoff frequency. ... An integrator is a device to perform the mathematical operation known as integration. ... // Definition Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. ...

SR = I sat / C A 2

where $I sat$ is the output current of the first stage in saturation.

Results from FactBites:

IC Logic Device Slew Rate and Rise Time (633 words)
	The slew rate of a device is the rate of change of it's output [from high to low, or from low to high].
	Don't allow digital logic slew rates to be slower than what is specified by the data sheet.
	Slew rate, and rise times is also effected by what is connected to the devices output.

SkylondaWorks Scrapbook Slew Rate (0 words)
	Slew rate is computed as the derivative of the time function.
	If a time series is considered as being comprised of its Fourier components, then the maximum slew rate is at the zero crossing of the highest large-signal sine function.
	As an example, a sine-wave of 1-volt maximum amplitude at a frequency of 1 MHz has a maximum slew rate of 6.28 volts/microsecond.

More results at FactBites »

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