Voltage-to-current converter

摘要

A voltage-to-current converter makes it possible to control conversion of a voltage to a current by considering the size of a transistor irrespective of supply voltage, input voltage, and fabrication conditions. It includes an operational amplifier (10) for receiving a constant-voltage source (VIN) to a noninverting terminal, and amplifying the voltage; a converting circuit (31) for converting the input voltage to current after receiving the output voltage from the operational amplifier as an input; a current mirror (32) for receiving the output current from the converting circuit as an input, and enabling two transistors of the current mirror to flow the same current; an electric potential holding circuit (33) for maintaining two electric potentials which are applied on respective drain terminals of the two transistors of the current mirror to be equal; and an output current mirror (34) for constantly maintaining current flowing out from the current mirror, which biases the electric potential of a drain terminal of the second transistor used in the current mirror with a predetermined value, and flows a constant voltage to the constant-current source output terminal. <IMAGE>