Why is there no virtual short in positive feedback?

If it is positive feedback, there is no control and the output keeps increasing which increases input and so on – thus removing any change of ‘virtual’ short or anything of that sort.

When virtual ground concept is not valid?

We go by the circuit analysis and if the gain comes equal to gain calculated by the virtual ground concept in case 1, then we say the virtual ground concept is valid otherwise not.

Why positive feedback is not used in op-amp?

In an op-amp circuit with no feedback, there is no corrective mechanism, and the output voltage will saturate with the tiniest amount of differential voltage applied between the inputs.

How virtual ground concept is considered in op-amp?

In opamps the term virtual ground means that the voltage at that particular node is almost equal to ground voltage (0V). It is not physically connected to ground. This concept is very useful in analysis of opamp circuits and it will make a lot of calculations very simple.

What is virtual short in opamp?

These concepts are helpful for gain calculation. You can conceptually understand a virtual short as follows. Typical differential amplifiers have a finite output voltage. The output voltage of an op-amp is equal to its gain multiplied by a difference in voltage between the two inputs.

What is meant by the virtual short concept in op-amp feedback circuits operating in the linear region?

A virtual short-circuit (or simply virtual short) refers to a condition of a differential input amplifier such as an op-amp in which its noninverting and inverting inputs have almost the same voltage. When the output voltage is finite, there is a very little difference in voltage (virtual short) between the two inputs.

What is the difference between real ground and virtual ground?

Real ground is when a terminal is connected physically to the ground or earth. where as virtual ground is a concept used in Op-Amps in which a node is assumed to have the potential that of the ground terminal.

Is not useful for linear applications closed loop configuration open-loop configuration linear amplification virtual ground?

As one of the reasons: There is no LINEAR application of opamps in open-loop configuration. The virtual ground does not necessarily imply the presence of negative feedback; it can be observed in an open-loop amplifier configuration as well.

What is the purpose of using positive feedback in amplifier?

Overview. Positive feedback enhances or amplifies an effect by it having an influence on the process which gave rise to it. For example, when part of an electronic output signal returns to the input, and is in phase with it, the system gain is increased.

Why negative feedback is used in amplifiers?

Negative feedback reduces gain of the amplifier. It also reduce distortion, noise and instability. This feedback increases bandwidth and improves input and output impedances. Due to these advantages, the negative feedback is frequently used in amplifiers.

Why is there a virtual short in op amp?

Why? Because “virtual short” is simply another way of saying that there is zero difference between the op amp’s two input voltages, and in real circuits the difference is “close enough” to zero. The open-loop gain of real op amps can be greater than 100 dB.

What is the difference between virtual short and virtual ground?

A virtual short-circuit (or simply virtual short) refers to a condition of a differential input amplifier such as an op-amp in which its noninverting and inverting inputs have almost the same voltage. When the input terminal on one side is grounded to GND as shown in the figure, it is sometimes called virtual ground.

Can we apply the virtual ground concept in op-amp configuration?

So, yes we cannot apply the virtual ground concept here. Similar is the case with the closed-loop configuration with positive feedback. The positive feedback closed-loop op-amp configuration has gain even greater than the open-loop gain A, thus going into saturation early, leading into hysteresis.

Why virtual ground concept is not valid for positive feedback systems?

Virtual Ground concept is not valid for positive feedback systems because positive feedback systems increases the gain, in case of positive feedback systems the difference voltage is equal to supply voltage + feedback voltage therefore we cannot adjust or make any change in supply voltage to bring input difference voltage to zero value.

How to control the gain of the op-amp using feedback resistor?

In this configuration, it is possible to control the gain of the op-amp using feedback resistor Rf and resistor R1. Ideally, the concept of the virtual ground is applicable when the op-amp is ideal and it is used in the linear range with negative feedback.

What is the ground potential of V1 and V2?

In the above circuit V1 is connected to ground, so V1 = 0. Thus V2 also will be at ground potential. Why we need Virtual Ground? Virtual Ground concept is very useful in analysis of an opamp when negative feedback is employed.