ANALOG SIGNAL TRANSMISSION CIRCUIT

摘要

PURPOSE:To avoid the application of the excessive input voltage to the analog switch by reducing the input-output terminal voltage of the analog switch under the allowance voltage via the Zener diode and then feeding to each OP amplifier and the analog switch from the common power source. CONSTITUTION:OP amplifier 12 operates on plus and minus power sources +VA and -VB. And MOSFET analog switch 6 switches the output of amplifier 12, can apply the voltage which is lower than potential VA+VB of the two power sources and higher than VA and VB respectively and furthermore increases and decreases the allowance voltage between input and output terminals 7 and 8 in accordance with the voltage between the terminals of the power source. Then potential difference VA+VB is applied between the power terminals of switch 6 after divided by Zener diode 14, and at the same time the voltage between terminals 7 and 8 is reduced under the allowance voltage via Zener diode 16 at the input side of switch 6. Thus the feeding is given to amplifier 12 and switch 6 from the common power source to avoid the application of the excessive input voltage to switch 6.