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- thirschbuechler commented on thirschbuechler's instructable DIY 1GHz* Active Probe for Under 20$**5 months ago
- thirschbuechler commented on MosfetN's instructable CleanBOT- Your DIY floor cleaning robot2 years agoView Instructable »
by clicking the link below his username you can find the test program on his site: http://bytechlab.pl/artykul-2
- thirschbuechler followed bertlds2 years ago
- thirschbuechler commented on thirschbuechler's instructable DIY 1GHz* Active Probe For Under 20$**2 years agoView Instructable »
2) If your 100MHz clock-signal is sinusoidial and relatively strong, your average passive probe probably will do fine. However, if you've got a non-sinusoidial (and/or weak signal), e.g. rectangular, your scope may show a worse representation due to relatively lowpass behaviour of the passive probe, meaning some of the harmonic components needed to form the signal may be cut off, as well as the measurement influencing the (weak) signal (by weakening it further).5) Probably ~400-500MHz limitation with FR4: The problem with FR4 is its relatively "Epsilon_r" (dielectric constant), so my guess is you may be able to work with that, but have to deal with more variation from board to board, as well as locally if you're unlucky, presumably especially at the output filter. Nevertheless...
see more » - thirschbuechler commented on thirschbuechler's instructable DIY 1GHz* Active Probe For Under 20$**2 years agoView Instructable »
Thanksfor asking! I can tell you straight away (Pages refer to the thesis):1)TheTermination can be omitted in principle if the cable-length L issmaller than the wavelength/2 (c=lambda * f, c=2/3 * speed-of-light(because of coaxcable)), since no standing waves can form (due toboundary conditions) and wavepropagation can be neglected. (i.e. 1ftcable = 0,3m → max. ~250MHz).3.1)No, the working point gets applied via R_bias, the second gate ismerely short-circuited for gain stabilisation. The 9V at the drain isthe supply, not the bias. I changed the setup-schematic to reflectthat ("ext. DC" referred to the thesis' experimental bias,oops..)3.2)see Page 7: "This [additional bias voltage] is required as theFet needs to work in the positive input voltage range, and withoutthe...
see more » - thirschbuechler favorited Side by Side Bicycle by carlitos2 years ago
unfortunately, there are no eagle files, since it was designed in NI AWR which is a RF design and simulation tool. The Circuit Diagram is shown in Step#2, after "C_out" the filter is appended. Which component placements do you need help with