Frequency mixer

In electronics, a mixer or frequency mixer is a circuit that outputs signals with new frequencies from two signals input to it. In its most common application, two signals are input and two signals are output, having frequencies equal to the sum and the difference of the original frequencies. Other frequency components may also be produced in a practical frequency mixer.

Mixers are widely used to shift signals from one frequency range to another, a process known as heterodyning, for convenience in transmission or further signal processing. For example, a key component of a superheterodyne receiver is a mixer used to move received signals to a common intermediate frequency. Frequency mixers are also used to modulate a carrier signal in radio transmitters.