What happens in the output stage?
The main function of the output stage is to deliver the output signal to the load. Since high signal levels are likely to occur, the output stage should be able to deal with high voltages and high currents. The resistive part of the load determines the maximum output current that is needed.
What does output stage mean?
n. 1 the act of production or manufacture. 2 (Also called) outturn the amount produced, as in a given period.
What does class AB mean?
Class AB amplifiers combine Class A and Class B to achieve an amplifier with more efficiency than Class A but with lower distortion than class B. This is achieved by biasing both transistors so they conduct when the signal is close to zero (the point where class B amplifiers introduce non-linearities).
Does Class A sound better than Class AB?
– A 30 watt Class “A” amp will sound louder than a 30 watt Class “AB” amp. – Because current is maximum at all times, the amp will have a smooth compression. – Lower power rating than a Class “AB” amp with the same tube configuration.
What do output transistors do?
The output transistors do not increase the size of the audio signal. Output transistors can only add current. Both NPN and PNP driver transistors manage the NPN and PNP output transistors collectively as compound single large Emitter followers with a high HFE current gain.
Which class amplifier has highest efficiency?
class D amplifier
The amplifier that has the highest efficiency is a class D amplifier. It has the highest power efficiency compared to other analogue classes such as A, B, AB, and C amplifiers.
How efficient is a class AB amplifier?
Class AB speaker amps offer high signal-to-noise (SNR), low THD+N, and typically up to 65% efficiency. A Class AB amp biases both transistors so that they conduct when the signal is close to zero. Thus, these amps provide more efficiency than Class A, with lower distortion than Class B.
How are power amplifiers classified in the output stage?
• Power amplifiers in the output stage are classified according to the percent (%) of time the output transistors are conducting (turned on): Class A:Output transistor is biasedat a quiescent current I Qand conducts for the entire cycleof the input signal. Class B: Output transistor conducts for only one-halfof each sine-wave input cycle.
How are transistors used in a class AB amplifier?
Class AB use a pair of transistors; both being biased slightly ON ensuring that the distortion complications around the crossover point associated with previous Class B amps is mostly eliminated. The transistors do not go into its full off range. This is achieved by implementing two diodes in the circuit.
What are the benefits of a Class A stage?
• Class A at very low bias, or bias on a class B stage • Removes conduction threshold, no crossover distortion • Small quiescent power dissipation 15 Elimination of harmonic distortion due to dead band, at the cost of efficiency and complexity.
Which is class AB amplifier overcome zero crossing distortion?
Construction of Class AB amplifiers are initiated to overcome zero crossing distortion in Class B amplifiers commonly called as Crossover Distortion.