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A in push pull pair the emitter of the two transistors are connected together. Therefore, what difference would it make if they are not matched vs if they are matched i.e they have same beta value.

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As the emitters are connected together they are working as emitter followers, with voltage gain = 1 (approximately).

If they are mismatched, you may see a slight increase in even order harmonic distortion, if the open-loop gain and feedback fraction are fairly low.

Some amplifiers may be a bit fussy about matching output transistors to ensure the designed value of quiescent current (and thus optimal crossover distortion), others may require a trimmer pot adjustment to achieve the right quiescent current. Without a circuit it's impossible to say more, so refer to the schematic and service manual for your amplifier.

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When the two transistors are running at very small signals they are both conducting .At larger signals there is a significant part of the cycle that only one device conducts .Hence matching Beta is more important for class B than class A. If you have an Amplifier with little or no negative feedback and your output transistors are poorly matched you will find that it sounds terrible on class B and good on class A .The follower type of output stage of course has local feedback reducing the negative impact of a transistor HFE mismatch . Most Amplifiers have lots of feedback so this affect is hard to notice .Simple circuits from the 1960s and 1970s would benefit from matching the output transistors when Dry cell battery operation precluded class A operation .Top end esoteric Audio has less negative feedback to keep TID down so would benefit from a matched pair .Most Audio Amplifiers are neither class A or B at moderate output powers .They are of course AB .The more class A the idle current setup is the less important output transistor matching is .The emitter resistors reduce the gain spreads in the output transistors due to the local negative feedback they produce.Higher value emitter resistors are normal for a class A setup for reasons of thermal stability of idle current .When the signal crosses the line from class A to Class B the were two transistors conducting and now there is one .This gives a small amount of open loop distortion which is worse with higher value emitter resistors .Remember that two devices have twice the transconductance of one .If this AB breakpoint is at high power nobody will hear a thing and you wont see it on the scope either.Full class A avoids this entirely .Otherwise do not go too high on the emitter resistors .

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