The other type of BJT is the PNP, consisting of a layer of N-doped semiconductorbetween two layers of P-doped material. A small current leaving the base is amplified inthe collector output. That is, a PNP transistor is "on" when its base is pulled low relative tothe emitter.The arrows in the NPN and PNP transistor symbols are on the emitter legs and point inthe direction of the conventional current flow when the device is in forward active mode.A mnemonic device for the remembering the symbol for a PNP transistor is pointing in(proudly), based on the arrows in the symbol and the letters in the name. That is, the PNPtransistor is the BJT transistor that is "pointing in".
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