physics (electronics - operational amplifier)

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By Nadeem Ramsing An electronic amplifier is a device for increasing the pow er of a signal. It does this by taking energy from a power supply and controlling the output to match the i nput signal shape but with a larger amplitude. The gain is a measure of the ability of a c ircuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output.  The gain of an amplifier is the ratio of output to input power, and is usually measured in decibels. The open-loop gain of an operational amplifier is the gain obtained when no feedback i s used in the circuit. y Typically an op-amp may have an open-loop gain of around 10 5 . The bandwidth of an amplifier is the range of frequencies for which the amplifier gives "satisfactory performance" The slew rate represents the maximum rate of change of a signal at any point in a circuit. (volts per second) The impedance describes a measure of opposition to alternating current (AC). Electrical impedance extends the concept of resistance to AC circuits, describing not only the relative amplitudes of the voltage and current, but also the relative phases. An Operational amplifier ("op-amp") is a DC-coupled high-gain electronic voltage amplifier with a differential input and a single-ended output. An op-amp produces an output v oltage that is typically hundreds of thousands times larger than the voltage difference between its input terminals. The gain of the inverting amplifie r is determined by the feedback resistor R2, and the input resistor R1. To minim ize tem erature dri ft R3 is

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Page 1: Physics (Electronics - Operational Amplifier)

8/7/2019 Physics (Electronics - Operational Amplifier)

http://slidepdf.com/reader/full/physics-electronics-operational-amplifier 1/2

By Nadeem Ramsing 

An electronic amplifier is a device for increasing the power of a signal. It does this by taking energyfrom a power supply and controlling the output to match the input signal shape but with alarger amplitude.

The 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. The gain of an amplifier is the ratio of output to input power, and is usually measured in decibels.

The open-loop gain of an operational amplifier is the gain obtained when no feedback isused in the circuit.

y Typically an op-amp may have an open-loop gain of around105.

The bandwidth of an amplifier is the range of frequencies for which the amplifier gives "satisfactoryperformance"

The slew rate represents the maximum rate of change of a signal at any point in a circuit. (volts per second)

The impedance describes a measure of opposition to alternating current (AC). Electrical impedanceextends the concept of resistance to AC circuits, describing not only the relative amplitudes of the voltageand current, but also the relative phases.

An Operational amplifier ("op-amp") is a DC-coupled high-gain electronic voltage amplifier with adifferential input and a single-ended output.

An op-amp produces an output voltage that is typically hundreds of thousands times larger than the voltage difference between its input terminals.

The gain of the inverting amplifier is

determined by the feedback resistor R2,

and the input resistor R1.

To minimize tem erature drift R3 is

Page 2: Physics (Electronics - Operational Amplifier)

8/7/2019 Physics (Electronics - Operational Amplifier)

http://slidepdf.com/reader/full/physics-electronics-operational-amplifier 2/2

By Nadeem Ramsing 

A comparator is a device that compares two voltages (or currents) and switches its output to indicatewhich is larger.

An ideal op-amp is usually considered to have the following properties, and they are considered to hold

for all input voltages:

  Infinite open-loop gain (If theres the slightest difference between the inputs, the output will saturate).

  Infinite voltage range available at the output (vout) (in practice, the voltages available from the output are limited by

the supply voltages and ).

  Infinite bandwidth (i.e., the frequency magnitude response is considered to be flat everywhere with zero phase shift).

  Infinite input impedance (so, in the diagram, , and zero current flows from to ).

  Zero input current (i.e., there is assumed to be no leakage or bias current into the device).

  Infinite slew rate (i.e., the rate of change of the output voltage is unbounded) and power bandwidth (full output

voltage and current available at all frequencies).

In a non-inverting amplifier , the output voltage changes in the same direction as the input voltage.

In an inverting amplifier, the output voltage changes in an opposite direction to the input voltage.