Main Page | See live article | Alphabetical index A differential amplifier is a type of electronic amplifier that multiplies the difference between two inputs by some constant factor (the gain). A common form of differential amplifier is the operational amplifier, or op-amp. Given two inputs A and B, a perfect differential amplifier gives an output O: where K is the gain. Note that a differential amplifier is a more general form of amplifier than one with a single input - by grounding one input of a differential amplifier, a single-ended amplifier results. Differential amplifiers are found in any system that utilises negative feedback, where one input is used for the input signal, the other for the feedback signal. A common application is for the control of motors or servos, as well as for signal amplification applications. In discrete electronics, a common arrangement for implementing a differential amplifier is the long-tailed pair, which is also usually found as the differential element in most op-amp integrated circuits. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.