I am designing PCB which has an FT601 for USB communication. No matter how hard I tried, I could not keep the traces short enough in order to avoid reflections and simulation was revealing significant overshoot and undershoot (>300 mV) so I decided to use termination resistors. The impedance of the traces is 50Ω so I am going to use this value or a value close to it. So far so good.
What I realized, then, is that this means a great number of resistors. The FT has 36 data lines, which means 72 resistors since they are bidirectional (according to what I have read I must terminate in both directions) as well as 5 other control lines resulting in a total number of around 80 resistors. And here come my questions, since I am a rookie in the high-speed design business:
What type of resistor? Should I use regular SMD resistors or an array in a chip? FTDI in their breakout board UMFT601 use those 33Ω chip arrays which I cannot identify. I did some research over component distributors and found some solutions but I did not notice any significant advantage (space, total price) of using a chip over normal SMD, apart from easier placement during design. Is there a standard approach to this situation?
Max distance between pin and resistor? How far the pin is OK to place the the resistors? I know they should be as close as possible but since the FT package is QFN the array (whether is chip or normal SMD) has to have some distance in order to achieve the connections properly.
Terminate both sides? Do I have to terminate both sides on the bidirectional pins? Most literature is focused and discuss one direction when analyzing signal integrity and I have not found many resources on the subject of bidirectional.