Basic Electronics Electrical How & Why

Op-Amps Basics-The Use and Applications of Operational-Amplifier (Op-Amps)

Basics of Op-Amps

Why do we need op amps? What are the different types of op amps?

01What are Op-Amp and Use of it?

Op-Amp are the basic building blocks of Analogue electronic circuits. They are the linear devices with all properties of a DC amplifier. We can use external capacitor or resistor to the Op Amp is many different ways to make them different forms of amplifies such as Non inverting amplifier, Inverting amplifier, Comparator, Voltage follower, Differential amplifier, summing amplifier, integrator etc. OPAMPs may be quad, dual, single etc. OPAMPs like CA3140, CA3130, TL0 71, LM311 etc have excellent performance with very low input current and voltage. In addition to other terminals, the ideal Op Amp has three important terminals. The input terminals are Non inverting input and Inverting input. The third terminal is the output which has sink and source current and voltage. The output signal is the amplifiers gain that multiplied by the value of the input signal.

025-Characteristics of Op-Amp:

  1. Open Loop Gain

Open loop gain is the gain of the Op Amp without a negative or positive feedback. An ideal OP Amp should have an infinite open loop gain but typically it range is between 20,000 and 2, 00000.

  1. Input Impedance

The input impedance is the ratio of the input current as is obvious from term input impedance to input voltage. The ratio of input current & voltage.It must be infinite without any leakage of current from the supply to the inputs. But there will be a few Pico ampere current leakages in most the Op Amps.

  1. Output Impedance

The ideal Operational Amplifier should have zero output impedance without any internal resistance. So that it can transfer full current to the load connected to the output.

  1. Band Width

In order to amplify any frequency from DC signals to the highest AC frequencies the ideal Op Amp should have an infinite frequency response. But mostly Op Amps have limited bandwidth.

  1. Offset

The output of the Op Amp should be zero when the voltage difference b/w the inputs is zero. But in most of the Op Amps, the output won’t be zero when off but there will be a minute voltage from it.

03Application of Op-Amp:

In this Article, I am going to discuss you some of the most important applications of Op-Amp. Below are the brief discussion of the some applications of Op-Amp.

Op-Amp as Inverting Amplifier:

The inverting circuits, implemented with an Op-Amp, are more constant, Provide a better transitory response, distortion is comparatively lower.

Op-Amp as Non Inverting Amplifier:

The input signal when applied to the non-inverting input (+), the output is applied back to the input via the feedback circuit created by Ri and Rf.

Op-Amp as Scale Chamber:

Op-Amp functions as a scale changer through small signals with constant-gain in both non-inverting and inverting amplifier.

Op-Amp as Logarithmic Amplifier:

The output voltage is proportional to the logarithm of the input voltage and it can be used as a logarithmic amplifier.

Vout=KT/Q  x  In( Vin/It  x  R )

op-Amp as Logarithmic Amplifier

Op-Amp as Half Wave Rectifier:

During the positive cycle of diode D2, Voltage is reversed biased as the positive signal is inverted by the op-amp. So there should be no output. However, during the negative cycle of the input voltage, the diode D2 is forward biased and conducts.

Op-Amp as Half Wave Rectifier


We will discuss the op-Amp in detail in the coming post.In this tutorial we have just discussed some configuration of op-amp but not how and where these will be used.Subscribe to our YouTube channel for How and why to use Tutorial series.Stay connected and feel free to comment below for any queries.

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Op-Amps Basics-The Use and Applications of Operational-Amplifier (Op-Amps)




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