This switched http://www.sohu.com/a/169362808_99967545
This is a frequently encountered problem: I want to 8Gbps PCIE test (also SAS / SATA / USB / LVDS etc.) serial bus, the oscilloscope line 16G will not do? 12G oscilloscope okay? Oscilloscope 8G line will not do? For high-speed serial bus, the oscilloscope in the end how much bandwidth is enough of it? The simplest method is a majority, assuming the signal is transmitted in the bus interval 0, the clock is a square wave, the fundamental frequency signal is 8Gbps 4GHz, in accordance with the principles of the bandwidth of 5 times, the bandwidth of the oscilloscope should 20GHz . In other words, the data rate is x2.5, is the recommended bandwidth. Not to say that 3 to 5 times the bandwidth of it? Why not three times? Cihao Duo money it ...... The answer is: Of course, 12GHz oscilloscope can measure the signal 8Gbps do? why not? Engaged in a test of people's eyes, is not okay, only whether the Right . Like now popular words, leave toxic dose to talk about is bullying. How does that look at whether the Right? Hands doing know. I BertScope made a 12Gbps (SAS3 rate), PRBS7, 500mV serial signal is transmitted to the SMA cable MS073304DX, 33GHz oscilloscope, then eye pattern test bandwidth limiting embodiment, 33GHz, 5.5 times the bandwidth, see a very good, oh, the measured rise time 30.7ps
25GHz, 4.2 times the bandwidth, oh no change, the rise time is measured 30.5ps
20GHz, 3.3 times the bandwidth, looked very good, oh, the rise time is measured to be 31.7ps
16GHz, 2.6 times the bandwidth, the edge of a significant change in the measured rise time is 37ps
12Ghz, 2 times the bandwidth, close to a sinusoidal measured rise time is 42ps
8GHz, 1.3 times the bandwidth, thicker lines starts, the rise time is 52ps measured
6GHz, based bandwidth, can barely read, the measured rise time of 140ps
5GHz, the bandwidth is not complete, I can not read ......
Look down the road, we should have a basic idea of the ordinary high-speed serial bus bandwidth demand, right? The accuracy requirements too high, the bandwidth of 4-5 times more than is necessary, starting from 3 times the bandwidth and accuracy of the rise time began to decline, and thus also affect the degradation of jitter parameters, a lot of high-speed serial bus conformance testing for the rise and fall time and jitter are all indicators required so to do conformance testing, try not to cut with. If only the measured eye diagrams, test results or error tolerance is relatively high, then reduce the number of the bandwidth test system is acceptable. Well, now 25.78Gbps electrical signals can not be tested with an oscilloscope 33GHz it? Look ~
Course is available. But if you want to conduct conformance testing, the best or the use of an oscilloscope, after all, in such a high speed, dynamic significant bit of the real-time oscilloscope and relatively low. of course can. 70GHz bandwidth is enough? The whole do not? For industrial purposes, 33GHz oscilloscope basic cover most of the applications, of course, if there is demand for higher bandwidth, welcome to us for support.
