Patent ID: 7903056

Claim:
A voltage-current converting method for converting an input voltage signal into a current signal and outputting the current signal, the method comprising steps of: connecting a source of a PMOS transistor to a first power source, connecting the source of the PMOS transistor to a signal input terminal via a coupling capacitor, and connecting a gate of the PMOS transistor and a drain of the PMOS transistor to a second power source to flow a current between the source of the PMOS transistor and the drain of the PMOS transistor while a constant voltage is applied to the signal input terminal, thereby charging a holding capacitor connected between the gate of the PMOS transistor and the source of the PMOS transistor; disconnecting the source of the PMOS transistor from the first power source, thereby discharging the holding capacitor through the PMOS transistor; disconnecting the drain of the PMOS transistor from the second power source, supplying the input voltage signal from the signal input terminal to the holding capacitor via the coupling capacitor, and connecting or continuing to connect the gate of the PMOS transistor to the second power source; and disconnecting the coupling capacitor from the signal input terminal, disconnecting the gate of the PMOS transistor from the second power source, connecting the drain of the PMOS transistor to the second power source, and connecting the source of the PMOS transistor to an output terminal, thereby outputting the current signal.