What is Additive mixing and Multiplative mixing in AM reception?
The two fundamental mixing modes are additive and multiplicative. Additive mixing is accomplished by adding the RF and Local Oscillator (LO) signals before applying them to a non-linear element. The large amplitude of the LO signal forces operation of the mixer device as a non-linear mixing element. Multiplicative mixing is accomplished when the RF and LO signals are applied to different terminals of the mixing element, with respect to a common terminal, such as in a double gate IGFET or a double balanced mixer (DBM). Additive mixing tends to yield a lower conversion gain, while multiplicative mixing with multi-electrode tubes tends to produce more noise unlike using a passive semiconductor DBM or DBM made with FETs which produce less noise.
