I received a task to review a board with ethernet controller W5100 from Wiznet and Ethernet Connector. It has SIM800L module as well ESP8266 uC. I cant give lot of details because confidentialitty. As I know, for ETH controller and Conn, It has differential signal pairs because ETH interface with RXIN, RXIP and TXON, TXOP RJ45 connector.
For this board, I have only 2 layers and I dont know if I need to decide and go through 4 layers because Ethernet Interface. I attached pictures from this layout and I would like suggestions how to improve it. Besides it theres a battery charger CI and holes where I will place a switch power supply module. I indicated So my questions:
1) Keep 2 layers or go through 4 layers? (1 gnd plane and 1 power plane, 2 signal layers)
2) How to make a correct differential pair for ethernet controller wiznet W5100, I did some serpentine to tune impedance on 50 ohms, and tune differential pair skew to 0mm.
3) Theres a need to use serpentine together with differential pair and which rules I should use, general rules, i find this reference design: https://wizwiki.net/wiki/doku.php?id...hardware:start
4) What to improve looking for this board?
5) I have SIM800L module, Esp8266 uController and Ethernet interface what to improve looking for this design and its reasonable this way or need to make rework, like place multilayers and its correct to use vias to do differential pair for ETH as was done? Well, whole board was done using auto router by coworker here...