Transistor switch with two control inputs

摘要

A transistor switching circuit is disclosed employing complimentary switching transistors which selectively connect either of two voltages to an output which is common to both switching transistors. Each of the switching transistors is driven by a constant current source. A diode is provided between a base and a collector of each of the switching transistors and the diode is positioned such that its polarity corresponds to the polarity of the base-collector junction of the respective switching transistor. A variable resistor may also be provided between the commonly connected bases and emitters of the switching transistors. Furthermore, the bases of the switching transistors may be coupled to the resistance by further diodes and each constant current source may also include a further transistor whose collector output connects to the input of the other current source.