# Explaining Symmetric Input in Instrumentational & Differential Amplifiers

• Garoll
In summary, the conversation is about understanding the difference between symmetric and non-symmetric inputs and outputs in instrumentational amplifier schematics and differential amplifiers. The conversation also includes a question asking for clarification on the meaning of "symmetric input" and a possible explanation involving a balanced differential input."
Garoll
I would like to ask you what it is meant by "symmetric input" in the instrumentational amplifier schematics and in the differential amplifier? I cant understand what is the difference between symmetric and non symmetric input and output as parameters. Can anyone explain ?

Thanks

Garoll said:
I would like to ask you what it is meant by "symmetric input" in the instrumentational amplifier schematics and in the differential amplifier? I cant understand what is the difference between symmetric and non symmetric input and output as parameters. Can anyone explain ?
Probably they mean a balanced diferential input, like

Vplus = A·sin(ωt), and

Vminus = -A·sin(ωt)

Bob S

## What is the purpose of symmetric input in instrumental and differential amplifiers?

Symmetric input is used in instrumental and differential amplifiers to maintain balance between the two input signals. It ensures that any noise or interference from the environment affects both inputs equally, resulting in a cleaner and more accurate output signal.

## How does symmetric input help improve the performance of amplifiers?

Symmetric input helps to reduce common mode noise, which is noise that is present in both inputs of an amplifier. This noise can interfere with the amplification of the desired signal, leading to inaccuracies in the output. By using symmetric input, the common mode noise is cancelled out, resulting in a more precise amplification.

## Can symmetric input be used in all types of amplifiers?

No, symmetric input is specifically designed for use in instrumental and differential amplifiers. These types of amplifiers are commonly used in applications where precise and accurate measurements are required, such as in scientific instruments and medical equipment.

## How is symmetric input achieved in amplifiers?

Symmetric input is achieved by using a balanced input circuit, where both inputs are connected to the same signal source through equal impedance paths. This ensures that any noise or interference is equally distributed between the two inputs, resulting in a balanced and clean output signal.

## What are some potential drawbacks of using symmetric input in amplifiers?

One potential drawback of using symmetric input is that it requires more complex circuitry, which can increase the cost and size of the amplifier. Additionally, if the balance between the two inputs is not maintained, it can result in distortion or noise in the output signal.

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