slew rate in opamp


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slew rate in opamp

  1. 1. Subject Code :151003 Name Of Subject Integrated Circuit and Application Name of Unit :The Practical Op-Amp Topic :Slew Rate & its equation Name 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
  2. 2. Slew Rate and its equationSub: ICA Topic: Slew Rate & its equation
  3. 3. The 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
  4. 4. • 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
  5. 5. The Operational Amplifier +VS i(-) _ Inverting RO vid Output Ri A vO = Advid Noninverting i(+) + -VSSub: ICA Topic: Slew Rate & its equation
  6. 6. • i(+), i(-) : Currents into the amplifier on the inverting and noninverting lines respectively • vid : The input voltage from inverting to non-inverting inputs • +VS , -VS : DC source voltages, usually +15V and –15V • Ri : The input resistance, ideally infinity • A : The gain of the amplifier. Ideally very high, in the 1x10 10 range. • RO: The output resistance, ideally zero • vO: The output voltage; vO = AOLvid where AOL is the open-loop voltage gainSub: ICA Topic: Slew Rate & its equation
  7. 7. • 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
  8. 8. •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
  9. 9. 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
  10. 10. This means the input stage takes a differential inputvoltage and produces an outputcurrent into the secondstage.The transconductance is typically very high — this iswhere the large open loop gain of the amplifier isgenerated. This also means that a fairly small inputvoltage can cause the input stage to saturate.In saturation, the stage produces a nearly constant outputcurrent.Sub: ICA Topic: Slew Rate & its equation
  11. 11. 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
  12. 12. 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 devices slew rate before using it for high-frequency applications.Sub: ICA Topic: Slew Rate & its equation