FEDEVEL
Platform forum

Parth , 06-23-2025, 05:45 PM

I am new to pcb.
The image that I have attached is of a esp32 dev board and the differential pair routed in green has no good return path so how does this board function well?
https://dl.espressif.com/dl/schematics/PCB_ESP32-S3-DevKitC-1_V1.1_20220429.pdf
This is link to schematic of the dev board

Parth , 06-23-2025, 06:12 PM

How Differential Pairs are routed on 2 layerd boards?

QDrives , 06-23-2025, 08:05 PM

Why not go for a 4 layer board?
What kind if signal is it?
Do you want to have it work reliable?

Parth , 06-24-2025, 04:08 AM

Isn't 4 layer going to be more expensive?
It's USB Signal
yes but it is not supposed to be like automotive grade or industrial

ElHeim , 06-24-2025, 03:41 PM

Depending on the manufacturer, 2/4 layers price difference might be negligible. Looking at OSHPark, the price for square inch is twice as much for the 4 layer one, but you have to weight that against the benefits of being able to have a power and ground plane in between the signal ones.

QDrives , 06-24-2025, 07:51 PM

Of course 4 layers is more expensive.
But you want it to work, right?

Parth , 06-25-2025, 03:43 AM

yes i want it to work

Parth , 06-25-2025, 03:48 AM

but my question was how does that pcb work , that is a official esp32 devkit pcb

Robert Feranec , 06-25-2025, 08:33 AM

two layer pcb 100x100mm $3.30

Robert Feranec , 06-25-2025, 08:33 AM

four layer PCB 100x100mm $12

Robert Feranec , 06-25-2025, 08:35 AM

I know it is more expensive, but in this case more expensive is still a good price. But of course it depends on how many products you are building.

Robert Feranec , 06-25-2025, 08:39 AM

You can route USB without controlled impedance and reference planes and it still may work fine. Sometimes there is no other way. Just then I try to keep it as short as possible (but it will still influence the quality of the signal)

Parth , 06-25-2025, 08:57 AM

ohk got it thanks