Subject Code :151003Name Of Subject Integrated Circuit and ApplicationName of Unit :The Practical Op-AmpTopic :Slew Rate & its equationName of Faculty : Mr. Jwolin Patel Mr.Yogesh Parmar Name of Students : (i) Savalia Avani(100870111020) (ii) Patel Jay (100870111021)

Sub: ICA Topic: Slew Rate & its equation

Slew Rate and its equation

Sub: ICA Topic: Slew Rate & its equation

The Operational AmplifierThe Operational Amplifier

• Usually Called Op Amps• An amplifier is a device that accepts a varying input

signal and produces a similar output signal with a larger amplitude.

• Usually connected so part of the output is fed back to the input. (Feedback Loop)

• Most Op Amps behave like voltage amplifiers. They take an input voltage and output a scaled version.

Sub: ICA Topic: Slew Rate & its equation

• They are the basic components used to build analog circuits.

• The name “operational amplifier” comes from the fact that

they were originally used to perform mathematical

operations such as integration and differentiation.

• Integrated circuit fabrication techniques have made high-

performance operational amplifiers very inexpensive in

comparison to older discrete devices.

Sub: ICA Topic: Slew Rate & its equation

The Operational AmplifierThe Operational Amplifier+V+VSS

-V-VSS

vvidid

InvertingInverting

NoninvertingNoninverting

OutputOutput

++

__ii(-)(-)

ii(+)(+)

vvOO = A = Addvvidid

RROO

AARRii

Sub: ICA Topic: Slew Rate & its equation

• ii(+)(+), i, i(-)(-) : Currents into the amplifier on the inverting and noninverting lines : Currents into the amplifier on the inverting and noninverting lines

respectively respectively

• vvidid : The input voltage from inverting to non-inverting inputs : The input voltage from inverting to non-inverting inputs

• +V+VSS , -V , -VSS : DC source voltages, usually +15V and –15V : DC source voltages, usually +15V and –15V

• RRii : The input resistance, ideally infinity : The input resistance, ideally infinity

• A : The gain of the amplifier. Ideally very high, in the 1x10A : The gain of the amplifier. Ideally very high, in the 1x101010 range. range.

• RROO: The output resistance, ideally zero: The output resistance, ideally zero

• vvOO: The output voltage; v: The output voltage; vOO = A = AOLOLvvidid where A where AOLOL is the open-loop voltage gain is the open-loop voltage gain

Sub: ICA Topic: Slew Rate & its equation

• In electronics, slew rate is a vector representing the maximum rate of change of a signal.• The slew rate of an electronic circuit is defined as the maximum rate of change of the output voltage. Slew rate is usually expressed in units of V/µs.

where is the output produced by the amplifier as a function of time t.

Sub: ICA Topic: Slew Rate & its equation

•The slew rate can be measured using a

function generator (usually square wave) and oscilloscope.

•The unit of slew rate is typically V/µs.

•The slew rate is same for both when feedback Is

considered or not considered.

Sub: ICA Topic: Slew Rate & its equation

There are slight differences between

different amplifier designs in

how the slewing phenomenon occurs.

However, the general principles are the

same as in this illustration.

The input stage of modern amplifiers is

usually a differential amplifier with

a transconductance characteristic. Sub: ICA Topic: Slew Rate & its equation

This means the input stage takes a differential input

voltage and produces an outputcurrent into the second

stage.

The transconductance is typically very high — this is

where the large open loop gain of the amplifier is

generated. 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.Sub: ICA Topic: Slew Rate & its equation

The second stage of modern power amplifiers 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 and gain , then

slew rate in this example can be expressed as:

Sub: ICA Topic: Slew Rate & its equation

Slew rate helps us to identify what is the maximum

input frequency and amplitude applicable to the

amplifier such that the output is not distorted. Thus it

becomes imperative to check the datasheet for the

device's slew rate before using it for high-frequency

applications.

Sub: ICA Topic: Slew Rate & its equation