Voltage-to-current converting circuit operating with low supply voltage

Abstract

A voltage-to-current converting circuit configured to convert an input voltage signal into a pair of complementary current signals by use of a current mirror, comprises a transistor 4 connected in the form of a diode and connected in series with a constant current source 21, a transistor 3 having a collector connector to a collector of the transistor 4, a transistor 2 having a base connected to a base of the transistor 3 so as to form a current mirror in cooperation with the transistor 3, the base of the transistor 2 being connected to receive an input voltage signal Vin, a bias circuit 5 for biasing the base of the transistors 3 and 2, and a transistor 1 having a base connected to a base of the transistor 4 so as to form a current mirror in cooperation with the transistor 4. The input voltage Vin is converted into a collector current I1 of the transistor 1 and a collector current I2 of the transistor 2. Thus, the voltage-to-current converting circuit is composed of only NPN transistors, so that a manufacturing process is simplified. In addition, since no emitter follower is included, a low voltage operation can be realized. This circuit can be applied to a multiplier, frequency doubler, a frequency mixer, etc.