| 摘要 |
PURPOSE:To attain correct switching even when a negative component is inputted as a control signal to be switched by connecting a diode to a signal input terminal of a switching circuit in a polarity that its cathode is directed to ground and using the diode so as to absorb the negative voltage. CONSTITUTION:The diode D1 is connected to a signal supply line while the anode is connected to ground. A transistor (TR3) is used for a control signal supply for an integrated circuit IC1, a switch SW2 is turned off when a control input voltage fed to a control terminal 4 is, e.g., at an L level, and a switch SW1 is turned on because the TR3 is cut off and offers an H level. A germanium diode is preferred to a silicon diode as to the diode D1 because the forward voltage drop VF of a silicon diode is nearly 0.7V, while that of a germanium diode is nearly 0.2V and the garmanium diode absorbs a negative voltage more easily than the silicon diode.
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