I. Thermal noise of resistor
The structure of the resistor and the mode of operation in the circuit determine the thermal effect of the resistor in the process of electrification, and all the components will heat up. The thermal effect is that when the temperature rises, the electrical conductors in the resistor will make irregular thermal movement, which will cause the directional flow of the current to fluctuate, thus forming the thermal noise current. This noise current will generate a noise voltage through the resistor, called thermal noise of the resistor.
II. Excess noise of resistance
At this stage, commonly used resistors of the industry include leaded resistors, MELF resistors, chip resistors and other special resistance products. In addition to the thermal noise, the resistor will produce another kind of noise, that is, excess noise, during the operation of the circuit. The resistor film is not uniform. When current passing through, it will not flow evenly through every region of the resistor. One of which must be more dense, so it will produce excess noise.
On the other hand, the resistance cylinder is composed of numerous conductive particles, and under the action of applied voltage, it produces irregular and not qualitative motion, and the resistance value will change accordingly, which will limit the current and thus produce excess current.
Excess current refers to the current noise of the resistance, which is related to the resistance, the current passing through, and the current intensity. All noise is harmful and unnecessary.
