htekin42
Member level 2
Dear All,
I am designing a board with FE1.1s and FTDI chips which are FT232RL and FT4232HL.
I am using 2 FE1.1s chip and get 4 usb port and different quantity serial port according to device model.
I have a question. I now that High Speed USB lines should be differential and they should be 90 ohm in differential. I am little bit confused. I used the saturn pcb tool to calculate impedance of lines.
I designed the board as 2 layer and top and bottom planes are Ground polygon. Gap is 0.245mm and PCB thickness is 1mm or 1.6mm, FR-4 standart and 1oz copper. When I calculate PCB tool, it gives me 1.2mm width of line. It is very bold line. How I can do correct line width. Also when I checked a few boards they have a line as seen in picture. What that is mean? I mean why designers make this kind of stuffs.
Thanks
I am designing a board with FE1.1s and FTDI chips which are FT232RL and FT4232HL.
I am using 2 FE1.1s chip and get 4 usb port and different quantity serial port according to device model.
I have a question. I now that High Speed USB lines should be differential and they should be 90 ohm in differential. I am little bit confused. I used the saturn pcb tool to calculate impedance of lines.
I designed the board as 2 layer and top and bottom planes are Ground polygon. Gap is 0.245mm and PCB thickness is 1mm or 1.6mm, FR-4 standart and 1oz copper. When I calculate PCB tool, it gives me 1.2mm width of line. It is very bold line. How I can do correct line width. Also when I checked a few boards they have a line as seen in picture. What that is mean? I mean why designers make this kind of stuffs.
Thanks