I have a question about TPA6132A2. In data sheet page 7 Fig1. , what's the difference between In Phase and Out of Phase. And how to measure it? Thanks.
Hi, Mino,
Welcome to e2e!!!
When we generate the curves for the data sheet, we use an Audio Precision. This outputs a sine wave, we apply it to the input of our amplifier, and connect the output of the amplifier to the analyzer input of the Audio Precision, and it can then measure the audio performance.
Out of phase refers to the left and rigth channels being 180 degrees out of phase:
The reason we do this is because the charge pump that supplies the current for the negative rail has some maximum current level. If the left and right channels are in phase, this doubles the current demanded from the charge pump, and it runs out of current earlier, limiting your power.
Since in audio left and right are not always correlated, and most people don't listen to sine waves, you could argue (we do!) that having the two outputs 180 degrees out of phase is a more realistic measurement to represent how the amplifier will be used in the real world.
TPA6132A2 is my favorite head phone amp! The noise floor is so low that I can't hear it! And, it has absolutely ZERO pop!
-d2
