The invention provides a voltage to current converter that contains an diode-connected NMOS transistor, a diode-connected PMOS transistor, and a voltage-controlled signal input circuit. The source of the NMOS transistor and the drain of the PMOS transistor are connected together and connected to the voltage-controlled signal input circuit in series. The invention is implemented and tested in the integrated circuit. When an input voltage signal is inputted, a current of the PMOS transistor is substantially linearly proportional to the input voltage signal.