how is a semiconductor used as a switch?
- lareLv 71 decade agoFavorite Answer
wow, some really confusing answers. here is the scoop. the name "semiconductor" means that the conductivity through the device can change. diodes are often used as RF switches. if the diodes has a forward DC voltage applied, ie it is conducting, then RF can ride through the diode essentially unaffected as long as the RF voltage is small compared to the DC bias. However if a reverse DC bias is applied to the diode, it is non-conductive. so unless the RF voltage is more than the DC bias, it can't get through the diode. Many radios and transcievers employ this function to direct RF voltages electronically without needing mechanical switches. The sense of the switch (on or off) is set by the applied DC voltage polarity.
- wiresLv 71 decade ago
A semiconductor, such as a transistor, can turn the current flow through it on and off with the correct bias on a control point. If the base of a transistor is bias correctly, this is the right polarity of voltage applied, it will cause the flow from collector to emitter to turn off or on.
The link below shows very understandable transistor switch diagrams.
- Stephen MLv 71 decade ago
Depending on how a transistor is biased, it can be used either as a switch or as an amplifier.