| 摘要 |
PROBLEM TO BE SOLVED: To reduce the number of necessary components. SOLUTION: This pressure-resistant analog switch circuit is provided with a high pressure-resistant junction type FET 71, resistances 72 and 73, a diode 74, and an NPN transistor 75. In this high pressure-resistant analog switch circuit, the voltage of the gate of the high pressure-resistance junction type FET 71 is held in the same level as that of the voltage of the source regardless of whether the voltage (the voltage of a signal inputted to a node Si) of the source is positive or negative so that any negative power supply voltage (-V) is dispensed with. Thus, it is necessary for a power supply voltage generating circuit 20 only to generated a positive power voltage (+V), and it is unnecessary to generate any negative power supply voltage (-V). Therefore, it is possible to reduce the number of components of the power supply voltage generating circuit 20 compared with the case the it is necessary to use the analog switch circuit in which the negative power supply voltage (-V) is necessary. As a result, it is possible to reduce costs. |
