| 摘要 |
PURPOSE:To obtain a switch circuit suitable for circuit integration and capable of attaining high dielectric strength to both positive and negative amplitudes by increasing the emitter area of the 2nd transistor (TR) more than that of the 1st TR so as to make the operating resistances equal to each other at conduction. CONSTITUTION:Collectors of the 1st and 2nd NPN TRs Q11, Q12 are connected in common, an emitter of the TRQ11 is connected to an input terminal Tin and an emitter of the TRQ12 is connected to a grounding point E respectively. In the switch circuit provided with the TRs Q11, Q12 like this, the emitter area of the TRQ12 is increased more than the emitter area of the TRQ11 so as to make the on-resistance of the TRs Q11, Q12 in the operating state equal to each other. That is, the relation of emitter area S(Q12E) 2S(Q11E) is attained. Thus, a reference voltage is grounded to a grounding level in a single power supply, and the switch circuit suitable for circuit integration where a high dielectric strength is obtained to both positive and negative amplitudes around the grounding level is attained.
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