| 摘要 |
PURPOSE:To improve on/off changing speed in changing signals by providing a switch control circuit in parallel to high pressure-proof analogue switches, and applying a differential voltage between a detection voltage and an on/off voltage to optically coupled circuits. CONSTITUTION:A switching circuit comprises high pressure-proof analogue switches 41'-4n' each comprising two electric field effect transistors 8a, 8b in inverse series connection to be used as a switching element, in which a voltage (eg) between their source gates is controlled by optically coupled circuits 9, 10 for connection between subject circuits to be changed. In addition, a switch control circuit 21 formed in a similar circuit constitution to that of the high pressure-proof analogue switch is provided in parallel to the high pressure-proof analogue switch, an amplifier 24 to detect the voltage (eg) between the source gates of the two electric field effect transistors 8a, 8b, and amplify a differential voltage between the detected voltage and an on/off reference voltage (r) is provided, and a negative feedback circuit to apply this amplified signal voltage to the optically coupled circuits 9, 10 inside the stitch control circuit 21 is provided. |
