| 摘要 |
PURPOSE:To obtain a constant voltage bias circuit which is stable against the fluctuation of power source voltage by arranging a constant current source which is compensated with respect to the fluctuation of the power source voltage and the variance of temperature and is stabilized. CONSTITUTION:A constant current source 28 is compensated with respect to the fluctuation of power source voltage and the variance of temperature and is stabilized to make the current, which is flowed to diodes 22-24 and the collector of a transistor TR20, constant against a variance of power source voltage and to make the bias voltage, which is given from a constant voltage bias circuit 29 to the base of a TR19, constant. Then, the base of a TR13 is biased by TRs 19 and 15, a diode 18, and resistance 14, 16 and 17. When a negative pulse is inputted from an input terminal 9, a TR7 is turned off through a resistance 8 only during the period of the pulse, and bases of TRs 5 and 4 are biased, and an AC signal inputted from an input terminal 12 through a capacitor 11 is detected. |
