Local oscillator

In electronics, the term local oscillator (LO) refers to an electronic oscillator when used in conjunction with a mixer to change the frequency of a signal. This frequency conversion process, also called heterodyning, produces the sum and difference frequencies from the frequency of the local oscillator and frequency of the input signal. Processing a signal at a fixed frequency gives a radio receiver improved performance. In many receivers, the function of local oscillator and mixer is combined in one stage called a "converter" - this reduces the space, cost, and power consumption by combining both functions into one active device.

The term local refers to the fact that the frequency is generated within the circuit and is not reliant on any external signals, although the frequency of the oscillator may be tuned according to external signals.