brief introduction: A mixer is a nonlinear three-terminal device, usually consisting of a diode or transistor operating in a nonlinear region. The mixer can add and subtract two input signals, and output their sum and difference. Depending on the configuration, this feature can be used for up -, down -, IQ mixers, or a variety of performance parameters. Mixers are commonly used in demodulation circuits, up and down converters for frequency conversion before or after transmission or reception. The frequency multipl