| 摘要 |
PURPOSE:To prevent malfunction with respect to an input signal with a negative level by providing a control circuit whose control transistor(TR) is connected between one output of a current mirror circuit leading out two identical output currents and an input terminal and operated in response to an output current of the other output. CONSTITUTION:A TR Q2 being a component of a current mirror circuit is formed in a semiconductor integrated circuit 1, a control TR Q1 connects between one output 7 and a line 9 connecting to a signal input terminal 6, and a reference voltage from a reference voltage generating circuit 11 is applied via a base line 10. When a negative voltage VG having a larger absolute value than the absolute value of an emitter voltage VCL of the TR Q1 from a signal source 6 to a resistor RIN, a TR Q6 locks in a current from an electric circuit 17 via a line 18 and the electric circuit 17 applies a predetermined operation. Thus, malfunction of the electric circuit 17 at the input of a negative signal is prevented. |
