| 摘要 |
PURPOSE:To eliminate the leakage current from a multiplexer being turned OFF by connecting the input of one multiplexer to ground while other multiplexer is turned ON and acting an output resistor to the multiplexer being turned ON as an emitter resistor. CONSTITUTION:Plural analog multiplexers 1-4-1, 1-4-2, 1-4-3 are connected to the output of an emitter follower 1-1 via output resistors 1-3-1, 1-3-2, 1-3-3. Analog switches 1-5-1, 1-5-2, 1-5-3 are operated by multiplexer selection signals CS0, CS1, CS2 to connect an input to multiplexers not selected to an emitter voltage VE. The emitter follower 1-1 has no emitter resistor and the combined output resistances connected to the voltage VE acts like the emitter resistor. When the analog multiplexer 1-4-1, e.g., is selected by the selection signal CS0, only the switch 1-5-1 is opened and the switches 1-5-2 and 1-5-3 are closed, then the output resistors 1-3-2, 1-3-3 are connected to ground and the parallel value of the two resistors acts like the emitter resistance.
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