# CM input range of instrumentation amp

• thistle
In summary, the common-mode (CM) input range of an instrumentation amplifier refers to the range of input voltages that can be applied to both input terminals without causing distortion or damage. It is different from the differential input range, which only applies to the positive and negative input terminals. The CM input range is affected by factors such as supply voltage, input impedance, and input signal characteristics. Exceeding the CM input range can result in saturation, clipping, or damage to the amplifier. The CM input range can be extended by using external components, but careful consideration is needed to maintain overall circuit performance.
thistle
Can anyone tell me how to calculate the common-mode input range of an instrumentation amplifier with all op-amps biased from +15V to -15V assuming all op-amps can swing rail to rail.

Thanks.

you should look at the specs on the datasheet for your amp

Looks like homework. And we'd need a schematic.

## What is meant by "CM input range" in an instrumentation amplifier?

The common-mode (CM) input range of an instrumentation amplifier refers to the range of input voltages that can be applied to both of the amplifier's input terminals without causing distortion or damage to the circuit. It is typically specified as a voltage range, such as +/- 10V.

## How is the CM input range different from the differential input range?

The differential input range of an instrumentation amplifier refers to the range of input voltages that can be applied to the positive and negative input terminals without causing distortion or damage to the circuit. It is typically specified as a voltage range, such as +/- 10V. The CM input range, on the other hand, refers to the range of input voltages that can be applied to both input terminals simultaneously without causing distortion or damage.

## What factors affect the CM input range of an instrumentation amplifier?

The CM input range of an instrumentation amplifier is affected by the supply voltage, the amplifier's input impedance, and the input signal's frequency and amplitude. In general, a larger supply voltage and a higher input impedance will result in a larger CM input range.

## What are the consequences of exceeding the CM input range of an instrumentation amplifier?

If the input voltage applied to both of the amplifier's inputs exceeds the specified CM input range, the amplifier may become saturated or experience clipping, resulting in distorted output signals. In extreme cases, exceeding the CM input range can also cause damage to the amplifier or other components in the circuit.

## How can the CM input range be extended in an instrumentation amplifier?

The CM input range of an instrumentation amplifier can be extended by using external components such as precision resistors or diodes to adjust the input impedance and limit the input voltage. This can help prevent saturation and distortion, allowing for a larger input voltage range. However, it is important to carefully consider the effects on the overall circuit performance before implementing any modifications.

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