Hello everyone, heres an quick overview of what the design does: the Si4703 radio tuner receives signals from the FM frequency band. Those signals will then get amplified by the PAM8008 module to output audio from the speakers. The current board stackup is sig/gnd/gnd/sig.

Some additional information about the parts:

• PAM8008 is a stereo amplifier that drives two 4 ohm speakers at 3W
• Will be using the STM32L432KC(chip) Dev board
• EA-DOGS164 is a 3.3v LCD screen that will display radio frequency, etc.

Some questions I have:

1. Is 4 layers necessary?
2. Would a pwr+sig/gnd/gnd/pwr+sig stackup work fine too? The reason I say this is because one of the power supply traces intersects with both the LOUT and ROUT output traces next to the Si4703, raising possible signal integrity concerns?
3. This is my first time working with antennas. I plan to use a ~75cm adjustable telescopic antenna and connect it with an SMA connector. I have it impedance matched at around 50 ohms, and made the length as short as possible with a ground plane underneath it. Are there any concerns with the antenna design?

Advice and suggestions are well appreciated, thanks in advance!

 

Pretty good design, 4 layers give you more flexibility. For LOW EMI and EMC I would suggest Sig/gnd/gnd/Sig. You can also use SIG/GND/PWR/SIG, that may not affect the much but give you more design flexibility. 50ohm track is good for the antenna.
I found an issue with RF and audio IC, due to RF component the noise may enter into the amlifying circuit. Although 2.4GHz may not amplified through it but some lower harmonics and thermal generated noise may cause the problem, avoid them placing closer to each other. I will suggest to separate the 3 parts a little bit away 1) digital mcu 2) analog amp 3) RF
I would also recommend to check the design once in a online DFM software free available and if you are going for a PCB then I will recomend to use JLCPCB, I got my all manufacturered PCBs from there and they offers great services.