Mixer phase

1. What is a mixer in signal processing?
2. What does a mixer do in RF?
3. Does a mixer add phase noise?
4. Is mixer linear or nonlinear?

What is a mixer in signal processing?

In electronics, a mixer, or frequency mixer, is an electrical circuit that creates new frequencies from two signals applied to it. In its most common application, two signals are applied to a mixer, and it produces new signals at the sum and difference of the original frequencies.

What does a mixer do in RF?

An RF mixer is a three-port passive or active device that can modulate or demodulate a signal. The purpose is to change the frequency of an electromagnetic signal while (hopefully) preserving every other characteristic (such as phase and amplitude) of the initial signal.

Does a mixer add phase noise?

This is why the noise figure is very nearly the conversion loss: the mixer does not add noise, but it does attenuate the signal by an amount equal to the conversion loss.

Is mixer linear or nonlinear?

The mixer, being a non-linear device, will produce, at its output, the two inputs (signals from the antenna and that from the oscillator), harmonics of them, their sum, their difference, harmonics of the latter two, sums and differences of all the above etc, etc.