[MOVED] 4 layer board Stackup

[zzm_3392]

Hi all,
I am designing a 4 layer board with total 1.2mm thickness. Based on the stackup, the line width of single 50 Ohm is 0.1835mm. But there are not suitable line width and gap for differential 200 Ohm. Can you give me a recommanded stackup which is suitable for both single 50 Ohm and 100 Ohm, or single 50 Ohm and differential 200 Ohm?
Thanks in advance!

 

[SughiRam P.]

I think u are asking 50 Ohm single ended trace width and 100 Ohm differential trace width.
7 mil trace on external layers will give u 50 Ohm impedance controlled trace, 6 mil trace width with 8 mil spacing between two traces will give u 100 Ohm differential impedance.
U can go for 6 mil trace width with 12 mil spacing even though they give 106 Ohm differential impedance if you have tolerance of +/- 10 Ohms.

 

[Antonios]

Try this stackup

 

[zzm_3392]

Hi SughiRam P.,
Thanks your advice. But differential impedance is 200 Ohm, not 100 Ohm.

---------- Post added at 03:17 ---------- Previous post was at 03:03 ----------

Hi Antonios,
Thanks. The 50 Ohm single ended trace is ok. But for 200 Ohm differential traces, there is not suitable trace width and gap.
Furthermore, the 6mil(0.15mm) width is small or not in practice for 50 Ohm transmission line.

 

[marce]

What signal requires 200 Ohm diff pair???

 

[zzm_3392]

It's a transceiver. The difference RX and TX are all matched to 200 Ohm, then transformed to single 50 Ohm by a balun HHM1521.