| 摘要 |
PURPOSE:To reproduce plural information with fidelity by providing a current switch switching a current at a high speed to a prescribed integration device among plural integration devices to apply accurate integration from a constant current source for a period only in response to a digital data. CONSTITUTION:Three contacts A, B, C are used and the contact C is connected to a point to which a current is thrown away such as a ground level point. A logic circuit 2 controls a switch 1 so that the contact C is connected when a control signal 131 is interrupted, the contact A is connected when a control signal 131 is set and a control signal 133 requires an output terminal 135, and the contact B is connected when the control signal 131 is set and the control signal 133 requires an output 136. The switch 1 consists of three transistors (TRs), all emitters are connected to the current source 136, and the TRs are controlled so as to make the emitter potential constant and the base potential of the conductive TRs the same potential, then the collector of the two TRs being the output is an imaginary ground and one TR is at a ground level, then the switch is switched very quickly. |
