emitter follower การใช้

• The emitter follower output stages could also be used to perform wired-or logic.
• It is determined by the upper output transistor V 3 operating in active region as an emitter follower.
• The high-resistive emitter element does not play any role it is shunted by the other low-resistive emitter follower.
• The row current capacity could be boosted by an NPN emitter follower instead of the typically much weaker I / O pin.
• For instance even a simple emitter follower has unity voltage feedback .  Preceding talk ) 00 : 11, 8 April 2008 ( UTC)
• Sziklai pairs are often used in the output stages of power amplifiers due to their advantages both in linearity and bandwidth when compared with more common Darlington emitter follower output stages.
• To alleviate this problem, " R " " C " is kept as low as possible and the amplifier is followed by a voltage buffer like an emitter follower.
• The output voltages at the collector load resistors R C1 and R C3 are shifted and buffered to the inverting and non-inverting outputs by the emitter followers T4 and T5 ( shaded blue ).
• As it exceeds the voltage required to bias the emitter-base junction of Q3, Q3 acts as an emitter follower or common collector amplifier and the base voltage of Q1 and Q2 begins to rise.
• Optimal quiescent current in an amplifier using Sziklai pairs also tends to be much lower than in Darlington-based output stages, on the order of 10mA vs . 100mA or more for some emitter follower output stages.
• Beginning in the early 1960s, ECL circuits were implemented on monolithic integrated circuits and consisted of a differential amplifier input stage to perform logic and followed by an emitter follower stage to drive outputs and shift the output voltages so they will be compatible with the inputs.
• While for decades the Quasi-complimentary output stage made sense, recently PNP and NPN power transistors have become roughly equally available and have more closely matched performance characteristics, and so modern audio power amplifiers often use equivalent topologies for both pairs, either both Darlington emitter follower or both Sziklai pair.
• The base voltage of the right transistor T3 is held fixed by a reference voltage source, shaded light green : the voltage divider with a diode thermal compensation ( R1, R2, D1 and D2 ) and sometimes a buffering emitter follower ( not shown on the picture ); thus the emitter voltages are kept relatively steady.
• In this bipolar junction transistor ( BJT ) implementation ( Figure 4 ) of the general idea above, a " Zener voltage stabilizer " ( R1 and DZ1 ) drives an " emitter follower " ( Q1 ) loaded by a " constant emitter resistor " ( R2 ) sensing the load current.
• If the frequency of your waveform is low ( less than, perhaps ten Hertz ), such a power supply could be used with any number of simple waveform-generation circuits to produce your desired effect . ( See function generator . ) Alternatively, consider an emitter follower connected between an ordinary constant voltage power supply and your load, with the'follower being driven by a waveform generator . ( Also, if your power requirements are small enough, you might find that a function generator itself can output the power directly . ) You can also buy " bipolar power amplifiers " that can help here, but they tend to be pricey.