Analogue multipliers are devices in a circuit that take two analogue signals and combine them into one. The output is the product of both of the inputs. For it to be a true analogue multiplier, the two inputs must be identical signals. If the two signals differ in voltage, the second will be scaled proportionally according to the level of the first, and this is called a voltage controlled amplifer.
What are analogue multipliers used for?
Analogue multipliers can be found in the control circuits of some industrial systems, as well as in radar circuitry. They are also used in frequency mixers.
Types of analogue multiplier
The key difference between analogue multiplier is the number of quadrants used: either one, two or four. One and two quadrant multipliers have simpler circuitry, and will therefore be the default if four quadrants are not needed.
Single quadrant multipliers are used when the signal is of only one polarity (either positive or negative).
Two quadrant multipliers can have one signal that is unipolar and another of either polarity.
Gilbert cells, or four quadrant multipliers, can cancel out unwanted signals as they are double balanced
