What causes intermodulation in an electronic circuit?

Intermodulation occurs when two or more signals mix together to create new, unwanted frequencies. This mixing process requires a nonlinear circuit or device, such as a diode or an overdriven amplifier, where the output is not strictly proportional to the input. In a perfectly linear circuit, multiple signals will simply pass through or be amplified without interacting to form new frequencies. However, practical components have some degree of nonlinearity, and when subjected to strong signals, they act like mixers, causing intermodulation. Distractors like positive or negative feedback affect amplifier gain and stability but do not inherently cause signal mixing. Lack of neutralization relates to preventing oscillation, not the fundamental generation of intermodulation products.