| 摘要 |
PURPOSE:To obtain a switch circuit which features the reduced passage loss of the signal carrier wave, the low power consumption, the easy switching of the signal polarity and the compact size. CONSTITUTION:The ratio is set for resistance R27 30 so that transistor Q25 and Q26 are switched off and on respectively when terminal 17 is opened. At this moment, diode D31 is turned on, the emitter current of the differential amplifiers of Q21 and Q22 flows to Q26 to secure the operation of the A-class amplification, and the signal carrier wave is supplied to load 11 from signal source 1. The base current of Q21 and Q22 is applied via R12 and R13 in common to the different circuit to be connected to output terminal 20 of input transformer 2, thus reducing extremely the power consumption. With supply of the earth signal to terminal 17, D31 and Q25 are turned off and on respectively with Q26, Q21 and Q22 turned off, and thus the carrier signal is stopped. When the connection switch is given by function 18 via R23 and R24, the switching operation can be facilitated for the signal polarity. Furthermore, the size can be minimized with adoption of the monolithic IC. |
