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What Is Offset Voltage?

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  • Written By: Jean Marie Asta
  • Edited By: Jessica Seminara
  • Last Modified Date: 18 December 2014
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    Conjecture Corporation
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Offset voltage is the result of a difference in voltage between the outputs of two operation amplifiers, or op amps. It is present in all real-world circuits where two op amps of opposing charges of the same value are grounded and yet still produce a small charge that is not quite zero. This can damage equipment used on the circuit, but there are many methods to correct this unwanted charge.

There are a variety of sources for offset voltage in a device. Adjusting the offset can fix this issue at the source. One way to do this is using input offset voltage, which adjusts the amount of volts put into a device to ensure that the output equals zero. This can be done using a potentiometer or a resistor to achieve the desired voltage. The value of the adjustments made to the input’s offset voltage can vary with temperature, so the environment the device will be used in should be considered if using this method.

The source for some offset voltage may be the amplifier itself. The design, position and even temperature of an op amp can affect the distribution of a charge throughout the circuit. Some modern op amps take this into account and detect the amount of offset voltage in the circuit. The amplifier then automatically adjusts its output into the circuit to ensure that the combined output is always zero.

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A voltage comparator is another device that is used to help minimize the difference between two amps in a circuit. These devices are attached to a circuit and give an accurate reading of the differences. The person working on designing the circuit can read and interpret the display on a voltage comparator and make changes to the circuit based on the difference displayed. The appropriate potentiometers and resistors can then be added to the circuit as necessary.

In many cases some offset voltage is unavoidable. When offset voltage can't be prevented, it is best to have the lowest amount possible to ensure the proper working of the circuit. Even a circuit with a very low offset voltage may be hazardous to use in some cases. Circuits can create feedback loops where the original small offset charge increases over and over, eventually becoming large enough to damage the circuit, other electronics, or cause harm to those who are working with it.

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