For some special resistors, the relationship between voltage and current is nonlinear. The resistor is the electronic circuit application quantity many components, usually forms the different series according to the power and the resistance value, the power supply circuit designer chooses. The resistor is mainly used in the circuit to adjust and stabilize the current and voltage, can be used as a shunt and voltage divider, but also as a circuit matching load. According to the requirements of the circuit, it can also be used for amplifying the negative feedback or positive feedback of the circuit, voltage-current conversion, voltage or current protection components in case of input overload, and can be composed of RC circuit as oscillation, filter, bypass, differential, integral and time constant components.