Voltage-to-current converter for outputting a current which varies in proportion to an input voltage

A voltage-to-current converter comprising:

• a first transistor of an emitter follower type having a base connected to an input terminal;
• a second transistor having a conductivity opposite to a conductivity of the first transistor, and including a base connected to an emitter of the first transistor, an emitter grounded through a first transistor, and a collector connected to an output terminal;
• a third transistor having characteristics which are the same as characteristics of the second transistor, and including a base connected to the emitter of the first transistor, and an emitter grounded through a second resistor;
• a current mirror circuit, connected to a collector of the third transistor and the emitter of the first transistor, for supplying a current identical to a collector current of the second transistor to the emitter of the first transistor;
• and
• a constant current source, connected to the emitter of the first transistor, for supplying a current, which is smaller than the current supplied from the current mirror circuit to the emitter of the first transistor, to the emitter of the first transistor when the converter is activated.

A voltage-to-current converter comprising:

• a first transistor of an emitter follower type having a base connected to an input terminal;
• a second transistor having a conductivity opposite to a conductivity of the first transistor, and including a base connected to an emitter of the first transistor, and a collector connected to an output terminal;
• a third transistor having characteristics which are the same as characteristics of the second transistor, and including a base connected to the emitter of the first transistor;
• a resistor having ends, one of the ends being connected to an emitter of the second transistor and an emitter of the third transistor, the other being grounded;
• and
• a current mirror circuit, connected to the emitter of the first transistor and a collector of the third transistor, for supplying a current identical to a collector current of the third transistor to the emitter of the first transistor.

A voltage-to-current converter comprising:

• a first transistor of an emitter follower type having a base connected to an input terminal;
• a second transistor having a conductivity opposite to a conductivity of the first transistor, and including a base connected to an emitter of the first transistor, and a collector connected to an output terminal;
• a third transistor having characteristics which are the same as characteristics of the second transistor, and including a base connected to the emitter of the first transistor;
• a resistor having ends, one of the ends being connected to an emitter of the second transistor and an emitter of the third transistor, the other being grounded;
• a current mirror circuit, connected to the emitter of the first transistor and a collector of the third transistor, for supplying a current identical to a collector current of the third transistor to the emitter of the first transistor;
• and
• a constant current source circuit, connected to the emitter of the first transistor, for supplying a current, which is smaller than the current supplied from the current mirror circuit to the emitter of the first transistor, to the emitter of the first transistor.

A voltage-to-current converter comprising:

• a first transistor of an emitter follower type having a collector grounded and a base connected to a non-inverted signal-input terminal;
• a second transistor having a conductivity opposite to a conductivity of the first transistor, and including a base connected to an emitter of the first transistor, and a collector connected to a non-inverted signal-output terminal;
• a third transistor having characteristics which are the same as characteristics of the second transistor, and including a base connected to the emitter of the first transistor;
• a first resistor having ends, one of the ends being connected to an emitter of the second transistor and an emitter of the third transistor, the other being grounded;
• a first current mirror circuit, connected to the emitter of the first transistor and a collector of the third transistor, for supplying a current identical to a collector current of the third transistor to the emitter of the first transistor;
• a fourth transistor including a collector grounded and a base connected to an inverted signal-input terminal;
• a fifth transistor having conductivity opposite to conductivity of the fourth transistor, and including a base connected to an emitter of the fourth transistor and a collector connected to an inverted signal-output terminal;
• a sixth transistor including a base connected to the emitter of the fourth transistor, and having the same conductivity and the same characteristics as the fifth transistor;
• a second resistor having ends, one of the ends being connected to an emitter of the fifth transistor, the other being grounded;
• and
• a second current mirror circuit, connected to the emitter of the fourth transistor and a collector of the sixth transistor, for supplying a current identical to a collector current of the sixth transistor to the emitter of the fourth transistor.