Electric current switch circuit and D/A converter using same

A D/A converter having a plurality of electric current switch circuits, each of the circuits which switches ON or OFF an electric current in response to an output of an IIL logic circuit, said each electric current switch circuit comprising:

• (a) a first transistor of NPN type, that has a base connected with an output terminal of the IIL logic circuit and a collector that is an output terminal through which the electric current flows, for switching ON or OFF the electric current;
• (b) a first resistor through which an emitter of the first transistor is grounded;
• (c) a first constant current source for supplying the base of the first transistor with a bias electric current;
• (d) a second transistor of PNP type, that has an emitter connected with the base of the first transistor and a collector that is grounded, for controlling a voltage of the output terminal of the IIL logic circuit;
• and (e) a voltage bias circuit for supplying the base of the second transistor with a bias voltage,
• wherein said plurality of electric current switch circuits are connected in series with each other in which the bases of the respective second transistors are commonly connected with each other.

An electric current switch circuit, comprising:

• an IIL logic circuit;
• a bias voltage generation circuit that generates a bias voltage;
• a first switching circuit that switches ON or OFF a constant electric current in accordance with whether the IIL logic circuit switches ON or OFF;
• and
• a control circuit to which the bias voltage is inputted, and which applies a voltage that is substantially equal to the bias voltage so as to switch ON the first switching circuit during switching OFF of the IIL logic circuit while switches OFF the first switching circuit during switching ON of the IIL logic circuit.