HI, Dear KlausST,
Thanks first.
The first picture output is the red noted P and N, which links to the female connector. But its input, by the vendor, who said the 560R is the terminal, before the 560R, there is a MIC with PTT used by user.
The second picture is no problem, because which has been used for many years, and my module has no audio issue with the 3rd and 4th partners. I just omitted unused circuit.
L1 and L2 are used for EMC, because the audio circuit is inserted in the same box with RF circuits.
I will check the BOM tomorrow , if we used with A suffix.
The power supply bulk capacitor is in another sheet which is the output of a LDO.
PCB layout is no problem, verified in many years.
I can't simply test because the vendor of 1st picture is 1000KM away, and I can only test in his lab, but in my lab, I can't verify.
So I want to clarify the root cause, and find all the possible cause, so that the test can be once done in the future.
So, it should not be matching issue? Any comments.
Many thanks.
Tony Liu
- - - Updated - - -
Hi, Dear FvM,
Yes, it's a power amplifier.
The other channel of MAX9719 is for earpiece, which has clear voice quality, so I omitted the other channel circuits.
So, what's the possible cause of the big noise?
Many thanks.
Tony Liu