| 摘要 |
PURPOSE:To switch easily a signal current level, by connecting the collector of a transistor for voltage-current conversion to a current mirror circuit and connecting the emitter to plural resistances which are switched to be connected. CONSTITUTION:When the control signal applied to an input terminal CTL is 0, an analog switch consisting of transistors TRs Q1 and Q2 is turned off, and a current Vin/(R1+R2) is flowed to resistances R1 and R2 by a signal voltage Vin applied to an input terminal IN, and a constant current due to a constant current source I1 is superposed in the emitter of a TRQ0, and the collector output current is flowed to the input terminal of a current mirror circuit R. A constant current due to a constant current source I2 is subtracted to output a signal current Iout=Vin/(R1+R2) to an output terminal OUT. When the control signal is 1, the analog switch is turned on, and the resistance R2 is short-circuited, and a current Vin/R1 is flowed to the resistance R1, and an output current Iout=Vin/R1 is outputted. |
