- #1

- 291

- 510

## Summary:

- - this seems to be a new way to cancel the Crossover Distortion in "Class-B" complementary transistor amplifier -

## Main Question or Discussion Point

Hello everyone, I was thinking how to cancel the class B crossover distortion, may I suggest to discuss an interesting variant.

Let's start from this:

- there is crossover distortion (and no current protection).

The signal source is "full voltage, zero current".

Let's make it "full current, zero voltage" :

Now the crossover distortion is cancelled, but the 5A source is too hard to make.

Let's try an input current transformer.

It must be without stray inductance and capacitance, to be equivalent to single coil with current:

In reality, adding a big input coil to the coil shown above causes stray HF resonance and great headache when developing the current source for high dV/dt and applying the general feedback to the whole amp.

But - how about moving the speaker to the right?

Now , the source current is 51 times less than output - so the source is quite possible to build even with the full voltage across it.

The voltage magnetizing the coil core is the follower error, practically only the crossover distortion, so the core non-linearity hardly matters.

My practical MicroCap simulation model seems working good, the current source is made of 4 Mosfets (2 in the differential input, 2 amplifying the current); the open-loop gain and overall feedback stability seem as good as in any classic amplifier.

The problem is very old MicroCap version I am using ; so if someone joins with a modern simulator, with modern components, the improvement may be very valuable.

Let's start from this:

- there is crossover distortion (and no current protection).

The signal source is "full voltage, zero current".

Let's make it "full current, zero voltage" :

Now the crossover distortion is cancelled, but the 5A source is too hard to make.

Let's try an input current transformer.

It must be without stray inductance and capacitance, to be equivalent to single coil with current:

In reality, adding a big input coil to the coil shown above causes stray HF resonance and great headache when developing the current source for high dV/dt and applying the general feedback to the whole amp.

But - how about moving the speaker to the right?

Now , the source current is 51 times less than output - so the source is quite possible to build even with the full voltage across it.

The voltage magnetizing the coil core is the follower error, practically only the crossover distortion, so the core non-linearity hardly matters.

My practical MicroCap simulation model seems working good, the current source is made of 4 Mosfets (2 in the differential input, 2 amplifying the current); the open-loop gain and overall feedback stability seem as good as in any classic amplifier.

The problem is very old MicroCap version I am using ; so if someone joins with a modern simulator, with modern components, the improvement may be very valuable.

Last edited: