I recently was looking at class AB amplifiers and had an 'idea' of how to reduce crossover distortion. The idea is to prevent Q1 from completely turning off by drawing a constant current I1 of around 1mA. Conversely I2 keeps Q2 from turning off completely. The value of the current source would be a compromise between losses and distortion reduction.
This circuit is only conceptual, it may need additional blocking diodes to protect the current sources. Nevertheless, if the transistors are kept just conducting, i.e. slightly on, then the crossover distortion would be reduced.
I'm sure I'm not the first to come up with this. What do people familiar with class AB design think of this?
This circuit is only conceptual, it may need additional blocking diodes to protect the current sources. Nevertheless, if the transistors are kept just conducting, i.e. slightly on, then the crossover distortion would be reduced.
I'm sure I'm not the first to come up with this. What do people familiar with class AB design think of this?
Kirchhoff's law suffers no exception, and the current sources will neutralize each other at all times, meaning the circuit with the current sources is exactly equivalent to the circuit without them.
To achieve your goal, you would need something like steering diodes, but in practice it will be complicated and the problems will be difficult to solve
To achieve your goal, you would need something like steering diodes, but in practice it will be complicated and the problems will be difficult to solve
Keeping both transistors conducting at all times is called a "non-switching" amplifier. Some manufacturers call this "Class A" which is not technically wrong but misleading.
Ed