| 摘要 |
PURPOSE: To prevent malfunction of the circuit by providing 1st and 2nd transistor(TR) connecting to a current source and configuring a differential pair and forming the 1st TR to be a diode-connected TR so as to allow the 1st TR to supply its own reference voltage. CONSTITUTION: For example, a TR 20 is conductive with a low level input at a node IN and a TR 22 is nonconductive. Thus, a TR 24 is conductive, emitters of the TRs 24, 26 have a level to reverse-bias an emitter-base voltage of the TR 26, then the TRs 26, 30 are nonconductive, resulting that a logically high level voltage Vcc appears at a node OUT. A current equal to a current I trough a constant current source 28 flows to a resistor 34. The voltage at the node OUT is nearly equal to Vcc-(I×R34). Thus, the voltage at the node OUT corresponds to a logic low level and the base-collector junction is always reverse-biased during the operation of the circuit, then malfunction is prevented.
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