| The dielectric constant of FR4 decreases with frequency. By roughly how much will the rise time of a signal be increased as it propagates through an FR4 stripline? |
| |
|
it depends : 13.18% (17) |
  
|
|
a negligible amount : 3.88% (5) |
|
|
0.15 psec/inch of path length : 5.43% (7) |
|
|
1.5 psec/inch of path length : 16.28% (21) |
|
|
15 psec/inch of path length : 16.28% (21) |
|
|
150 psec/inch of path length : 11.63% (15) |
|
|
not enough information to estimate : 33.33% (43) |
|
| | |
Comment made by Alexander Golian on 2010-02-20 12:29:40
|
| As frequecy increases the the loss attributed to the dielectric becomes frequecy dependent. I would expect the formula should read 0.15dB/inch/GHz. Hence, not enough info.... |
Comment made by Vadim Voronov on 2010-04-02 09:41:49
|
| Polar Instruments simulator reveals that losses rises 1db/inch for stripline 0.1/0.1/0.1/18um/4.2 Capacitance and inductance rises with losses the same manner 10 times/10inch. So rise time will increase but how much in numbers need more info. |
Comment made by Benny Christensen on 2010-04-06 00:55:53
|
| Some time ago I made a characterisation of our 10 Gbit/s parallel OE devices on FR4 / 100 um Rogers 4450, 260 um width transmission lines. On purpose, one channel was 4 cm shorter and resulted in a RMS extraction of 9.5 ps / root (cm) trace length for a chip rise-time of approx. 30 ps. |
Application Notes
