darlington pair การใช้

• Another drawback of the Darlington pair is its increased " saturation " voltage.
• The Darlington pair has more phase shift at high frequencies than a single transistor and hence can more easily become unstable with negative feedback ( i . e ., systems that use this configuration can have poor phase margin due to the extra transistor delay ).
• Darlington pairs are available as integrated packages or can be made from two discrete transistors; Q 1 ( the left-hand transistor in the diagram ) can be a low power type, but normally Q 2 ( on the right ) will need to be high power.
• Likewise, in a typical application the collector of Q2 ( also connected to the emitter of Q1 ) plays the role of an emitter and is thus labeled " E . " As with a Darlington pair, a resistor ( e . g ., 100? & ndash; 1k? ) is usually connected between Q2's emitter and base to improve its turn-off time ( i . e ., its performance for high frequency signals ).