Left side = electrode input, that goes into an electro discharge protection ic then into the resistor arrays then into the capacitor arrays then into the ads 1299.
Right side = Female input pins that connect to the spi lines of the ads1299 and dvdd power. I will plug in an esp32 dev board with short jumper wires. the esp will be powered off of the same power as the ads1299 pcb power. (3.3v regulator).
Top side (power) = I will plug in an external battery that will go into 3.3v regulator then into the charge pump. The dvdd power will come off of a parallel branch of the 3.3v regulator output. The ads1299 analog power 2.5 and -2.5v will come from the charge pump.
I got it as good as I can, I am kind of confused about the return paths.
PCB BOARD SPECS = 4 layers. SIGNALS/GND/POWER/SIGNALS. POWER PLANES ARE ON POWER LAYER. RED TRACES ARE TOP LAYER. BLUE LAYER IS BOTTOM LAYER
ADS1299 = ADC CONVERTER
LDL1117S33R = 3.3V REGULATOR
LM27762DSSR = CHARGE PUMP WITH 2.5V AND -2.5 REGULATED OUTPUT
ESD PROTECTION IC'S = TPD4E1B06DCKR
RESISTOR ARRAYS = CAY16-2201F4LF
CAPACITOR ARRAYS = CKCL44X7R1H102M085AA
PLEASE REVIEW MY FIRST PCB. EEG, analog/digital.
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avareed
- Posts: 2
- Joined: 08 Nov 2025, 08:25
- Location: 27 Strickland Street, Denmark WA 6333, Australia
Re: PLEASE REVIEW MY FIRST PCB. EEG, analog/digital.
Great job taking on an EEG board as your first PCB — that’s a challenging mix of analog and digital signals. A few general things to watch for when you ask for detailed feedback:
Analog front end: Make sure the high-impedance EEG inputs are kept far from digital traces, clocks, and switching regulators. Any noise here will show up in your signal.
Grounding: Use a solid analog ground plane and keep it separated from digital ground until a single, intentional connection point.
Power supply: Clean, low-noise rails are essential. Decoupling caps should be close to every analog IC pin.
Trace routing: Keep the analog section short, shielded, and isolated. Route digital lines away from sensitive inputs.
Safety: Since this touches a human body, double-check input protection — diodes, resistors, and isolation where required.
For a first board, the most important thing is layout discipline and understanding where noise can creep in. If you share the schematic or layout, people will be able to offer much more precise feedback, but you’re definitely on the right track tackling a design like this.
Analog front end: Make sure the high-impedance EEG inputs are kept far from digital traces, clocks, and switching regulators. Any noise here will show up in your signal.
Grounding: Use a solid analog ground plane and keep it separated from digital ground until a single, intentional connection point.
Power supply: Clean, low-noise rails are essential. Decoupling caps should be close to every analog IC pin.
Trace routing: Keep the analog section short, shielded, and isolated. Route digital lines away from sensitive inputs.
Safety: Since this touches a human body, double-check input protection — diodes, resistors, and isolation where required.
For a first board, the most important thing is layout discipline and understanding where noise can creep in. If you share the schematic or layout, people will be able to offer much more precise feedback, but you’re definitely on the right track tackling a design like this.
Stay curious, keep building, and share what you learn.